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authorTobias Weingartner <weingart@cvs.openbsd.org>1997-09-25 01:59:05 +0000
committerTobias Weingartner <weingart@cvs.openbsd.org>1997-09-25 01:59:05 +0000
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treebe3f8a73d9276efac2dfa18313a1655c62555f19
parente0dfe4f1d3a2adadecae6598b89035949cbe5f0a (diff)
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+ ATA/ATA-1/ATA-2/IDE/EIDE/etc FAQ
+
+ Part 1 of ? -- The Basics
+
+ Version 0b -- 7 Feb 95
+
+ by Hale Landis -- landis@sugs.tware.com
+
+Note: Major changes from the previous version are marked by a
+ "!" at the left margin on the first line of the changed
+ paragraph.
+
+First the "legal" stuff...
+
+ 1) This FAQ is not intended to replace any other FAQ on this
+ subject but is an attempt to provide historical and technical
+ information about the ATA interface.
+
+ 2) This FAQ is not an endorsement of any vendor's product(s).
+
+ 3) This FAQ is not a recommendation to purchase any vendor's
+ product(s).
+
+ 4) Every effort is made to insure that all of the information
+ presented here is not copyrighted, not proprietary and
+ unrestricted.
+
+ 4) When opinions are stated they are clearly identified,
+ including the person's name and email address. Such opinions
+ are offered as long as they contribute to the understanding of
+ the subject being discussed. No "flames" allowed.
+
+This is the first version of this FAQ. It will take some time to
+get all the significant information into it so it will be rapidly
+growing and changing during the next several weeks or months. I
+don't even know how many parts there will be yet! Versions will
+be numbered with simple integer numbers (no 1.1, 1.2, etc)
+starting at 0.
+
+If you have a question that is not answered here or if you have
+unrestricted material that you would like to contribute, please
+email it to landis@sugs.tware.com. DO NOT send material that is
+copyrighted, proprietary or otherwise restricted in any way -- I
+can't use such material in this document.
+
+I don't have FTP access to anything at this time so I leave it to
+others to put this at the appropriate FAQ FTP sites.
+
+About myself: Until recently I worked for Seagate where I was
+one of several people that attended the ATA, ATA-2, PCMCIA and
+SFF meetings for Seagate. I was also the manager of a software
+development group that created much of the engineering test
+software for ATA hard disk drives. I am now a consultant and I
+still attend the ATA-2 meetings.
+
+Table of Contents
+-----------------
+
+Part 1 - The Basics
+
+ Glossary
+ Basic Questions
+
+Part 2 - BIOS and Drivers
+
+ TBD
+
+
+Glossary
+--------
+
+Read and understand these terms. You will be lost and confused
+if you don't! Many of these are describe in much greater detail
+in other parts of this FAQ.
+
+ATA or AT Attachment
+
+ ATA is the proper and correct name for what most people call
+ IDE. In this document, ATA refers to all forms of ATA (ATA-1,
+ ATA-2, etc, IDE, EIDE, etc). The ATA interface uses a single
+ 40-conductor cable in most desktop systems.
+
+ATA-1
+
+ ATA-1 is the common name of the original ATA (IDE)
+ specification. ATA-1 is not an official standard yet. Final
+ approval is pending.
+
+ATA-2 or ATA Extensions
+
+ ATA-2 is the common name of the new ATA specification. ATA-2
+ is still in early draft form and has not been submitted for
+ approval as an official standard.
+
+ATA-3
+
+! ATA-3 is the common name of a future version of the ATA
+ specification. The ATA-3 working group has held several
+ meeting but the only things adopted so far are a DMA
+ version of the Identify command, a description of
+ "device 1 only configurations" and a set of "security"
+ commands.
+
+! There is much discussion going on concerning merging ATA-3
+ with ATAPI. This will require some kind of "command overlap"
+ capability. The details of this are consumming much of the
+ meeting time.
+
+ATAPI or ATA Packet Interface
+
+ ATAPI is a proposed new interface specification. Initially it
+ will probably be used for CD-ROM and tape devices. It uses
+ the ATA hardware interface at the physical level but uses a
+ subset of the SCSI command set at the logical level. The
+ ATAPI specification work is currently being done in the SFF
+ committee.
+
+! The ATAPI folks have delayed forwarding their CD-ROM
+ specification from SFF to X3T10 so the X3T10 ATAPI working
+ group has nothing to work on yet and have held no meetings.
+
+! Block Mode
+
+! Block mode is the name given to the use of the ATA Read
+ Multiple and Write Multiple commands. These commands generate
+ a single interrupt to the host system for each block of
+ sectors transfered. The traditional Read Sectors and Write
+ Sectors commands generate an interrupt to the host for each
+ sector transfered.
+
+CAM (Common Access Method) Committee
+
+ The Common Access Method committee, now disbanded, worked on
+ two specifications: the CAM SCSI and CAM ATA specifications.
+ Both specifications were forwarded to the X3T9 committee for
+ further work years ago.
+
+CHS or Cylinder/Head/Sector
+
+ CHS is the old and traditional way to address data sectors on
+ a hard disk. This style of addressing relates a sector's
+ address to the position of the read/write heads. In today's
+ ATA devices, all sector addresses used by the host are logical
+ and have nothing to do with the actual physical position of
+ the sector on the media or the actual position of the
+ read/write heads.
+
+Command Block
+Control Block
+
+ These are names given to the I/O register interface used by
+ ATA devices. It refers to a set of I/O registers, or I/O
+ ports and I/O port addresses used to program the device.
+ These names replace the older term Task File.
+
+DMA or Direct Memory Access
+
+ DMA is a method of data transfer between two devices that does
+ not use the system's main processor as part of the data path.
+ DMA requires lots of hardware: a DMA arbitration unit, a DMA
+ data transfer unit and host bus signals that enable the DMA
+ controller to assume control of the host system's bus. When
+ the DMA controller has control of the host system's bus, it
+ moves data between the two devices by generating the
+ appropriate bus read/write cycles. For the ATA READ DMA
+ command this means generating an I/O read cycle and then a
+ memory write cycle for each 16-bit word being transferred.
+ For the ATA WRITE DMA command, a memory read cycle is followed
+ by an I/O write cycle for each 16-bit word transferred.
+
+EIDE or Enhanced IDE
+
+ EIDE is a marketing program started by Western Digital to
+ promote certain ATA-2 features including ATAPI. WD has
+ encouraged other product vendors to mark their products as
+ "EIDE compatible" or "EIDE capable".
+
+ESDI
+
+ See MFM.
+
+Fast ATA
+
+ Fast ATA is a Seagate marketing program used to promote
+ certain ATA-2 features in newer ATA devices. Seagate has
+ encouraged other product vendors to mark their products as
+ "Fast ATA compatible" or "Fast ATA capable".
+
+Host or Host System
+
+ The computer system that the ATA device is attached to.
+
+HBA or Host Bus Adapter or Host Adapter
+
+ The hardware that converts host bus signals to/from ATA
+ interface signals. An ATA-1 host adapter is generally a very
+ simple piece of hardware. An ATA-2 host adapter can be simple
+ or complex.
+
+IDE
+
+ IDE can mean any number of things: Imbedded Device (or Drive)
+ Electronics (yes, you can spell embedded with an "i"),
+ Intelligent Device (or Drive) Electronics, etc. The term IDE
+ is the trademark of someone (Western Digital does not claim
+ IDE as theirs but they do claim EIDE). Many hard disk vendors
+ do not use IDE to describe their products to avoid any
+ trademark conflicts.
+
+LBA or Logical Block Addressing
+
+ LBA is a newer (for ATA it is newer) way to address data
+ sectors on a hard disc. This style of addressing uses a
+ 28-bit binary number to address a sector. LBA numbers start
+ at zero. In today's ATA devices, all sector addresses used by
+ the host are logical and have nothing to do with the actual
+ physical location of the sector on the media.
+
+Local Bus
+
+ Usually this refers to the processor's local bus in a high
+ performance computer system. Usually the processor, the
+ external processor instruction/data cache, the main memory
+ controller and the bridge controller for the next low speed
+ system bus, for example, a PCI bus, are located on the local
+ bus. Lower speed local buses may have connectors that allow
+ the attachment of other devices. For example, the VL-Bus is a
+ local bus that can allow attachment of video, SCSI or ATA
+ controllers. It is very difficult to attach other devices to
+ high speed (say faster than 100MHz) local buses due to
+ electrical restrictions that come into play at those higher
+ speeds.
+
+Master
+
+ ATA device 0. Device 0, the master, is the "master" of
+ nothing. See Slave.
+
+Megabyte or MB
+
+ Megabyte or MB is 1,000,000 bytes or 10^6 bytes. IT IS NOT
+ 1,048,576 bytes or 2^20 bytes, repeat NOT!
+
+MFM
+
+ In this document MFM refers to any of the older hard disk
+ controller interfaces, MFM, RLL and ESDI. It is used to
+ describe any hard disk controller that uses the Task File
+ interface on the host side and the ST506/ST412 interface
+ on the drive side.
+
+OS
+
+ Operating System.
+
+PC Card ATA
+PCMCIA
+
+ We can thank the Personal Computer Memory Card International
+ Association for the PC Card specification. The PCMCIA is a
+ nonprofit industry association. The PC Card ATA
+ specification is another form of the ATA interface used by
+ PCMCIA compatible ATA devices. This interface uses the PCMCIA
+ 68-pin connector. Most 68-pin ATA devices are dual mode --
+ they can operate as either a PCMCIA PC Card ATA device or as a
+ 68-pin ATA device.
+
+PCI
+
+ We can thank Intel and the other members of the PCI committee
+ for the PCI bus specification. PCI is intended to be the next
+ high performance computer bus. PCI is not generally described
+ as a processor local bus.
+
+PIO or Programmed Input/Output
+
+ PIO is a method of data transfer between two devices that uses
+ the system's main processor as part of the data path. On
+ x86 systems, the REP INS and REP OUT instructions
+ implement this data transfer method. INS reads and I/O port
+ and writes the data into memory. OUTS reads data from memory
+ and writes the data to an I/O port. Each time an INS or OUTS
+ instruction is executed, the memory address is updated. The
+ REP prefix causes the instructions to be repeated until a
+ counter reaches zero.
+
+RLL
+
+ See MFM.
+
+Slave
+
+ ATA device 1. Device 1, the slave, is a "slave" to nothing.
+ See Master.
+
+Task File
+
+ This is the name given to the I/O register interface used by
+ MFM controllers. It refers to a set of I/O registers, or I/O
+ ports and I/O port addresses used to program the controller.
+ In ATA, this name has been replaced by the terms Command Block
+ and Control Block.
+
+SCSI
+
+ See the SCSI FAQ.
+
+SFF or Small Form Factor
+
+ The SFF committee is an ad hoc committee formed by most of the
+ major storage device and system vendors to set standards for
+ the physical layout of hard disk and other devices. SFF has
+ published many specifications that describe the physical
+ mounting and connector specifications for hard disk devices,
+ including ATA devices. During a brief period of time when the
+ X3T9 committee was not doing much work on the ATA-1 interface,
+ the SFF committee published several specifications that were
+ not really part of the original SFF charter. Most, if not
+ all, of these nonphysical specifications have now been
+ incorporated into the latest X3T9 or X3T10 ATA specifications.
+ ATAPI is currently an SFF specification.
+
+ST506 and ST412
+
+ This is the common name for the hard disk controller to hard
+ disk drive interface used by MFM, RLL and ESDI controllers and
+ disk drives. ST stands for Seagate Technology. The ST506 and
+ ST412 were the Seagate products that set the de facto
+ standards for this interface many years ago. This interface
+ is composed of two cables: a 34-conductor and a 20-conductor
+ cable.
+
+VESA and VL-Bus
+
+ We can thank the Video Electronics Standards Association for
+ the VESA Local Bus or VL-Bus specification. The VL-Bus is one
+ example of a local bus. VESA is a nonprofit industry
+ association like the PCMCIA.
+
+WG or Working Group
+
+ The actual work on various specifications and standards
+ documents within the X3T9, X3T10 and SFF committees happens in
+ working group meetings. Most WG meetings are held monthly.
+
+X3T9 and X3T10
+
+ These are the names of the official standards committees that
+ have worked on the ATA-1 and ATA-2 specifications. X3T9 was
+ responsible for the SCSI and ATA-1 specifications and
+ standards. X3T10 has replaced X3T9 and is now responsible for
+ the current SCSI and ATA specifications and standards work.
+
+528MB
+
+ This term is used in this document to describe the capacity
+ boundary that exists in most x86 system software. This
+ boundary limits the size of an ATA disk drive to 528MB. For
+ cylinder/head/sector style addressing of disk data sectors,
+ this number is computed as follows:
+
+ a) the number of cylinders are limited to 1024, numbered
+ 0-1023.
+
+ b) the number of heads (per cylinder) are limited to 16,
+ numbered 0-15,
+
+ c) the number of sectors (per track) are limited to 63,
+ numbered 1-63.
+
+ d) a sector is 512 bytes,
+
+ e) 528MB means the following values:
+
+ ( 1024 * 16 * 63 ) or 1,032,192 data sectors
+
+ or
+
+ ( 1024 * 16 * 63 * 512 ) or 528,482,304 bytes.
+
+68-pin ATA
+
+ This refers to a variation of the ATA interface that uses the
+ PCMCIA 68-pin physical interface but does not use the PCMCIA
+ electrical or logical interface. Most 68-pin ATA devices are
+ dual mode -- they can operate as either a PCMCIA PC Card ATA
+ device or as a 68-pin ATA device. This interface was
+ developed within the SFF committee and is now included in
+ ATA-2.
+
+Basic Questions
+---------------
+
+### Where did ATA come from?
+
+ What we now call the ATA-1 interface was developed for Compaq
+ many years ago by Imprimus (then part of CDC, now part of
+ Seagate) and Western Digital. The first ATA-1 hard disk
+ drives were made by Imprimus but it was Conner that made the
+ interface so popular.
+
+### How is ATA different from MFM?
+
+ From the host software standpoint, ATA is very much like the
+ Task File interface used by MFM controllers. A properly
+ written host software driver should not notice any difference
+ between the MFM Task File interface and the ATA Command Block
+ interface while doing basic commands such as Read/Write
+ Sectors.
+
+ At the hardware level, ATA uses a single cable between a host
+ bus adapter and the ATA device, where the MFM controller
+ interface uses two cables between the controller and the
+ drive.
+
+ In the MFM environment, the controller is one piece of
+ hardware and the drive another piece of hardware. Most likely
+ these two pieces of hardware are from different vendors. The
+ MFM controller is dependent on the design of both the host bus
+ and on the drive.
+
+ In the ATA environment, the host adapter is the one piece of
+ hardware that is dependent on the host system bus design. The
+ ATA interface is (mostly) system independent. All of the
+ hard disk controller and drive logic is contained in the ATA
+ device hardware. This gives the hard disk designer complete
+ control over both the controller and drive functions.
+
+### Why is ATA so popular?
+
+ Two basic things make ATA so popular today: cost and hard
+ disk drive technology. An ATA-1 host adapter is cheap,
+ usually much less than $25US and it uses only one cable. On
+ the technology side, current hard disk features, such as,
+ defect handling, error recovery, zone recording, cache
+ management and power management require that the controller be
+ fully integrated with the read/write channel, the servo system
+ and spindle hardware of the disk drive.
+
+### What are the basics of the ATA interface?
+
+ The ATA interface is a very simple interface based on an ISA
+ bus I/O device architecture. The interface consists of two
+ sets of I/O registers, mostly 8-bit, for passing command and
+ status information. The registers are like a set of mail
+ boxes with a door on front and back connected such that both
+ doors can not be open at the same time. The front door is
+ open when the Busy bit in the Status register is zero and the
+ host can read and write the registers. The back door is open
+ when the Busy bit in the Status register is one and the ATA
+ device can read or write the registers.
+
+ The physical interface contains just enough signals for a 16
+ bit data bus, five register address bits, and a few control
+ signals like read register, write register and reset.
+
+ ATA devices look like traditional hard disk
+ drives even though some are not really a hard disc with
+ rotating platters. User data is recorded in 512 byte sectors.
+ Each sector has a sector address. There are two ways to
+ express sector addresses: by cylinder/head/sector (CHS) or by
+ logical block address (LBA). CHS is standard, LBA is optional.
+
+### What is EIDE or Fast ATA?
+
+ Both are marketing programs used to promote various ATA-2
+ features, mostly the faster data transfer rates defined by
+ ATA-2.
+
+ ---
+
+ WD defines EIDE as:
+
+ * Support for drives larger than 528MB.
+
+ * Support for two connectors to allow up to four drives.
+
+ * Support for CD-ROM and tape peripherals.
+
+ * Support for 11.1/16.6 Mbytes/second, I/O Channel Ready PIO
+ data transfers.
+
+ * Support for 13.3/16.6 Mbytes/second, DMA data transfers.
+
+ ---
+
+???Seagate defines Fast ATA as:
+
+ * Support for PIO mode 3 (11.1 MB/sec) and DMA mode 1(13.3
+ MB/sec).
+
+ * Support for Multi-sector [Read/Write Multiple] transfers.
+
+ * Support for >528 MB.
+
+ * Support for Identify Drive Extensions & Set Transfer Mode
+ Extensions.
+
+ * Backward compatibility with ATA-1.
+
+ ---
+
+ What does all of this mean to us?
+
+ Support for the ATA-2 high speed PIO and DMA data transfer
+ modes is both a hardware and software issue.
+
+ Support for more than one hard disc controller (or ATA host
+ adapter) requires the BIOS and/or the operating system to
+ support more than one Task File or Command/Control Block
+ register set on the host bus.
+
+ The 528MB problem is due to the original design of the x86
+ BIOS which limits cylinders to 1024 and sectors to 63. The
+ ATA interface allows up to 65,535 cylinders, 16 heads and 255
+ sectors -- that's about 136GB (137GB if is LBA is used).
+ Support for devices over 528MB requires the BIOS and/or
+ operating system to support some form of CHS translation.
+ Note that LBA alone does not solve this problem (in fact,
+ LBA may make things more complex).
+
+ Support for CD-ROM and tape will probably be done via the
+ ATAPI interface which uses a different command structure than
+ ATA. That makes ATAPI another host software issue.
+
+### What does an ATA-1 host adapter do?
+
+ An ATA-1 host adapter is a simple piece of logic whose main
+ purpose is to reduce the system bus address lines from 12 (or
+ more) down to 5. It may also buffer some signals giving some
+ degree of electrical isolation between the host bus (usually
+ an ISA or EISA bus) and the ATA bus. In ATA-1, the ATA
+ interface is controlled directly by the host bus so that all
+ timings are controlled by the host bus timing.
+
+### What does an ATA-2 host adapter do?
+
+ This answer is complex because it depends on how smart your
+ ATA-2 host adapter is. First, an ATA-2 host adapter supports
+ the ATA-2 higher speed data transfer rates. That requires
+ that the host adapter is attached to something other than an
+ ISA or EISA bus. Second, an ATA-2 host adapter may perform
+ 32-bit wide transfers on the host bus. This requires FIFO
+ logic and data buffers in the host adapter. Third, an ATA-2
+ host adapter may use a different data transfer protocol on the
+ host side than is used on the ATA device side.
+
+! ### Can I put an ATA-2 device on an ATA-1 host adapter?
+! ### Can I put an ATA-1 device on an ATA-2 host adapter?
+
+ The answer to both questions is yes, as long as the electrical
+ timing specifications of the device are not violated. In
+ general it is impossible for an ATA-1 host adapter to violate
+ the specifications of an ATA-2 device. It is possible for an
+ ATA-2 host adapter to violate the timing specifications of an
+ ATA-1 device but this is not common. Hoever, host adapter
+ hardware design errors or software driver bugs can cause such
+ a problem. The result will be corrupted data read or written
+ to the ATA-1 device.
+
+! ### I have an ATA-2 host adapter with an ATA-2 device. I want to
+! ### add an ATA-1 device to this host adapter. Can I run the ATA-2
+! ### device in its ATA-2 data transfer modes?
+
+ Sorry, *NO* you can *NOT* run the new drive in its faster data
+ transfer modes. Be very careful, most of the ATA-2 host
+ adapter vendors don't have anything in their setup
+ documentation or software to prevent this sort of thing.
+
+ When you run the new drive at a data transfer speed that is
+ faster than the older drive can support, you are violating the
+ electrical interface setup and hold times on the older drive.
+ There is no telling what the older drive will do about this,
+ but you are asking for data corruption and other nasty
+ problems on your older drive.
+
+### How many disk controllers and/or ATA host adapters and/or
+### SCSI host adapters can I put in my system?
+
+ From a hardware standpoint -- as many as you want as long as
+ there are no I/O port address, memory address or interrupt
+ request signal conflicts. From a software standpoint it is a
+ whole different story.
+
+ First the simple x86 system hard disk controller
+ configurations...
+
+ a) 1 ATA with 1 or 2 drives at I/O port addresses
+ 1Fxh/3Fxh using interrupt request 14 (IRQ14).
+
+ b) 1 ATA with 1 drive at I/O port addresses 1Fxh/3Fxh
+ using interrupt request 14 (IRQ14) plus a SCSI with 1 drive.
+
+ c) 1 SCSI with 1 or 2 drives.
+
+ Other configurations are possible but are most likely not
+ supported in the system or SCSI host adapter BIOS. And if its
+ not supported at the BIOS level, it is unlikely to be
+ supported by an operating system, especially DOS. The primary
+ reason the above configurations are so restrictive is that the
+ original IBM x86 BIOS supported only one MFM controller with a
+ maximum of 2 drives. This restriction was then coded into
+ much x86 software including many early version of DOS. The
+ configurations above work because they don't break this old
+ rule.
+
+ Just remember this -- most systems will always boot from
+ the first drive on the first controller. In a) that is
+ ATA drive 0, in b) that is ATA drive 0, in c) that is
+ SCSI drive 0.
+
+ And now the more complex configurations...
+
+ Once you go beyond the three configurations above all bets are
+ off. Most likely you will need operating system device
+ drivers in order to access any drives beyond the first two.
+ And now your real problems start especially if you like to run
+ more than one operating system!
+
+ If you do run more than one OS, then you need equivalent
+ drivers for each system if you would like to access all the
+ drives. Plus it would be nice if all the drivers configured
+ the drives in the same manner and supported all the possible
+ partitioning schemes and partition sizes. It would be
+ especially nice if a driver would not destroy the data in a
+ partition just because it did not understand the file system
+ format in that partition.
+
+ One of the things EIDE promotes is BIOS support for up to four
+ ATA devices -- 2 ATA host adapters each with 1 or 2 drives.
+ The first would be at I/O port addresses 1Fxh/3Fxh using
+ interrupt request 14 (IRQ14) and the second at I/O port
+ addresses 17xh/37xh using interrupt request 15 (IRQ15).
+ Acceptance of this configuration has not been spreading like
+ wild fire through the BIOS world.
+
+ Lets look at a two complex configurations...
+
+ a) 1 ATA with 2 drives and 1 SCSI with 1 or more drives.
+
+ Nice configuration. The ATA drives would be supported by the
+ system BIOS and the SCSI drives may be, could be, should be,
+ supported by the SCSI host adapter BIOS but probably not. So
+ in order to use the 2 SCSI drives you probably have to disable
+ the BIOS on the SCSI card and then load a device driver in
+ CONFIG.SYS. And because the SCSI BIOS is disabled, you then
+ need a SCSI driver for that other OS you run.
+
+ b) 2 ATA with 1 or 2 drives on each.
+
+ Also a nice configuration. But because the system BIOS
+ probably only supports the first controller address, you'll
+ need a DOS device driver loaded in CONFIG.SYS in order to
+ access the drives on the second controller. You'll need that
+ driver even if there is only one drive on the first
+ controller. You also need a similar driver to support the
+ second controller in your other OS.
+
+ Note: I understand that OS/2 does support both MFM/ATA
+ controller addresses and does allow up to four drives -- I
+ have not confirmed this for myself.
+
+! ### Are disk drives the only ATA devices?
+
+ No. Over the years there have been ATA tape drives, ATA
+ CD-ROMS and other strange devices. Most of these are expected
+ to be added to an existing ATA host adapter as the second
+ device (device 1) with an existing ATA disk drive (device 0).
+ In general these require software drivers to operate with your
+ OS.
+
+ Now, we have ATAPI CD-ROM and tape devices that can be placed
+ on an ATA host adapter. And soon we should see system
+ motherboard BIOS support for booting from an ATAPI CD-ROM
+ device. The general idea is that an ATAPI device can coexist
+ with an ATA device on the same cable.
+
+! ### What can be done to improve ATA device performance?
+
+ A difficult question. But the first step is usually to reduce
+ the number of interrupts that the host sees during a read or
+ write command. ATA disk drives have three types of read/write
+ commands:
+
+ * Read Sectors / Write Sectors -- These commands are the old
+ traditional data transfer commands. These commands generate
+ one interrupt to the host for each sector transfered. These
+ are PIO data in and PIO data out commands which use the host
+ processor to transfer the data.
+
+ * Read Multiple / Write Multiple -- These commands where
+ defined in ATA-1 but were not used very much until recently.
+ These commands generate one interrupt to the host for each
+ block of sectors transfered. The number of sector per block
+ is generally 4, 8 or 16. However, when 1 sector per block is
+ used, these commands are the same as the Read/Write Sectors
+ commands. These are PIO data in and PIO data out commands
+ which use the host processor to transfer the data.
+
+ * Read DMA / Write DMA -- These commands where defined in
+ ATA-1 but were not used very much until recently. The main
+ reason for not using them was that x86 system DMA transfer
+ rates are much slower than PIO. However, these command do
+ generate a single interrupt at the completion of the command.
+
+ Now see the next question...
+
+! ### What else can be done to improve ATA device performance?
+! ### -or-
+! ### What is PIO mode "x" ?
+
+ An even more difficult question. The second step is usually
+ to increase the rate at which the host transfers data.
+
+ (Ahh... I can see the funny look on your face from here. You
+ are saying to yourself: "the rate at which the host transfers
+ data? doesn't this guy have things backwards?" Read on...)
+
+ The rate at which data is transferred to or from an ATA device
+ is determined by only one thing: the PIO or DMA cycle time
+ the host uses. No, the drive does not have much to do with
+ this! The only requirement is that the host not exceed the
+ minimum PIO or DMA cycle times that the device supports. For
+ example, during a PIO read command when the device signals an
+ interrupt to the host this means that the device is waiting
+ for the host to read the next sector or block of sectors from
+ the drive. The host must execute a REP INSW instruction to do
+ transfer the data. The rate at which the host executes this
+ instruction determines the PIO cycle time. Technically, for a
+ read command, the cycle time is the time from the host
+ assertion of the I/O Read signal to the next time the host
+ asserts the I/O Read signal.
+
+ Be careful when looking at the table below -- the data rate is
+ the data transfer rate achieved while transfering the sector
+ or block or sectors. It is an "instantanous" data rate. The
+ overall data transfer rate for a command includes many time
+ consuming events such as the amount of time the host requires
+ to process an interrupt. Note that on many fast ATA drives
+ today, the time it takes the host to process an interrupt is
+ frequently greater than the time required to transfer the
+ sector of block of sectors for that interrupt! It is not
+ uncommon for the host overhead to reduce the data rate to 1/2
+ or 1/3 of the instantanous rate shown here.
+
+ The ATA PIO modes are defined as follows:
+
+ PIO min cycle data comment
+ mode time rate
+
+ 0 ???ns ?MB the rate at which a system
+ running at 4.77MHZ could
+ execute the REP INSW.
+
+ 1 ???ns ?MB the rate at which a system
+ running at 6MHz could
+ execute the REP INSW.
+
+ 2 240ns 8MB the rate at which a system
+ running at 8MHz could
+ execute the REP INSW.
+
+ 3 180ns 13MB requires an ATA-2
+ host adapter.
+
+ 4 120ns 16MB requires an ATA-2
+ host adapter.
+
+ The complete description of the PIO (and DMA modes is much
+ more complex and will be cover in more detail later in this
+ FAQ.
+
+### Do I need BIOS or OS drivers to support more than 528MB?
+
+ Warning: Read the previous question before reading this one.
+
+ Maybe, probably, yes. The answer to this *very* complex and
+ will be discussed in detail in Part 2. Here is the brief
+ answer...
+
+ A traditional x86 system BIOS supports only CHS mode
+ addressing with cylinders limited to 1024, heads limited to 16
+ and sectors limited to 63. This allows addressing of drives
+ up to 528MB. These limitations come from the INT 13
+ read/write calls that combine a 10-bit cylinder number with a
+ 6-bit sector number into a 16-bit register.
+
+ Note that this is entirely a software problem: the ATA
+ interface supports up to 65,535 cylinders, 16 heads and 255
+ sectors.
+
+ While the head number usually requires only 4-bits, up to 6 or
+ 8 bits are available in the INT 13 interface. This fact has
+ allowed the SCSI folks to support big drives by increasing the
+ number of heads above 16. The SCSI host adapter BIOS converts
+ this "fake" CHS address to a different CHS or an LBA when it
+ issues a read/write command to the drive. The following table
+ shows some approximate drives sizes and the "fake" CHS
+ parameters that you may see from a SCSI BIOS:
+
+ cyl head sector size
+
+ 1024 16 63 512MB
+ 1024 32 63 1GB
+ 512 64 63 1GB
+ 1024 64 63 2GB
+ 1024 256 63 8GB
+
+ The last entry represents the largest possible drive that
+ a traditional INT 13 BIOS can support.
+
+ The system BIOS folks *must* start supporting drives over
+ 528MB in their BIOS by implementing some type of CHS
+ translation. To date, few systems have such BIOS. And here
+ is the bad part: Microsoft says that the BIOS *must*
+ support it in order to use it in their OS. The algorithm is
+ simple (but warning: this is not the complete algorithm!):
+
+ INT 13 input action ATA interface
+
+ cyl number "multiply" by n modified cyl number
+ head number "divide" by n modified head number
+ sector number nothing sector number
+
+ The value of n must be selected such that the modified head
+ number is less than 16.
+
+ LBA addressing at the hard disk drive level or at the BIOS or
+ driver level is another solution. This solution will probably
+ not be popular for several more years. It requires that the
+ BIOS people implement a new INT 13 interface, called the
+ Microsoft/IBM Extensions and that the OS people start using
+ this new BIOS interface. Few system BIOS support this
+ alternative interface today. Without this new interface, LBA
+ support at the hard disk drive level is not required.
+
+ So most of us have older systems without much possibility of
+ getting a BIOS upgrade, so what do we do? Well we must obtain
+ one of the many driver products that are on the market that
+ live in one of the disk boot sectors and "take over" the
+ system BIOS INT 13 with an INT 13 that supports the
+ translation. The biggest problem with this is that the
+ replacement INT 13 BIOS must live someplace in memory. For
+ DOS based systems, it can usually live at the top of the 640K
+ of memory and DOS is made to think that that part of memory,
+ usually around 8K bytes, does not exist. But the protected
+ mode OS's don't like this and usually wipe out the driver when
+ they load their kernel. So if you plan to run multiple OS's
+ on your system, buyer beware!
+
+ Then there is the Windows problem: the standard FastDisk
+ driver in Windows does *not* support such translation schemes
+ and can not be enabled. So make sure the driver you
+ purchase also comes with a Windows FastDisk replacement.
+
+ Buyer beware!
+
+### Do I need BIOS or OS drivers to support the ATA-2 data
+### transfer rates?
+
+ Warning: Read the previous two questions before reading this
+ one.
+
+ Maybe, probably, yes. The answer to this *very* complex and
+ will be discussed in detail in Part 2. Here is the brief
+ answer...
+
+ If you have a new ATA drive that supports the advanced PIO or
+ DMA data transfer rates (ATA-2 PIO Mode 3 or 4, or, ATA-2 DMA
+ Mode 1 or 2) then you also must have a new ATA host adapter
+ that attaches to the VL-Bus or PCI bus or some other high
+ speed bus (probably a 32-bit bus) in your system. That host
+ adapter has I/O registers of its own that are used to control
+ its advanced features. Controlling those advanced features
+ requires software -- either in the system INT 13 BIOS or in a
+ INT 13 BIOS on the host adapter card or in a driver loaded
+ via the boot record or later by your OS.
+
+ Depending on how that host adapter works you may also
+ need a Windows FastDisk replacement in order to use the high
+ speed data transfer modes in Windows.
+
+ Buyer beware!
+
+### I just purchased a new high speed host adapter for my VL-Bus
+### (or PCI bus) system and a new 540MB hard disk. How do I get
+### full use out of all this new hardware?
+
+ Did you read the previous three questions?
+
+ You need BIOS or driver software and a Windows FastDisk
+ replacement. These *must* support both CHS translation
+ (because your drive is over 528MB) and the host adapter
+ hardware (to use the high speed data transfer rates).
+
+ Some drivers on the market today use LBA addressing on the
+ ATA interface to get over 528MB. This may make your disk
+ partition(s) unreadable by another OS.
+
+ Check the hardware and software specifications of the product
+ before you buy it! Ask lots of questions -- you probably get
+ lots of incorrect or misleading answers -- be prepared for
+ that! If you plan to run something other than DOS and
+ Windows, especially if you plan a "dual boot" or "boot
+ manager" environment, be real careful.
+
+ Buyer beware!
+
+ OPINION: I know of only one product that supports all of this
+ new hardware, supports over 528MB *and* supports most of the
+ current OS's that are shipping including several in shipping
+ in beta form. The product is from a small two person company
+ that is trying to sell the product on an OEM basis and not in
+ the retail market. - Hale Landis <landis@sugs.tware.com>
+
+/end part 1/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//
diff --git a/etc/etc.i386/INSTALL.chs b/etc/etc.i386/INSTALL.chs
new file mode 100644
index 00000000000..e93a748c1a0
--- /dev/null
+++ b/etc/etc.i386/INSTALL.chs
@@ -0,0 +1,890 @@
+ How It Works -- CHS Translation
+
+ Plus BIOS Types, LBA and Other Good Stuff
+
+ Version 4a
+
+ by Hale Landis (landis@sugs.tware.com)
+
+THE "HOW IT WORKS" SERIES
+
+This is one of several How It Works documents. The series
+currently includes the following:
+
+* How It Works -- CHS Translation
+* How It Works -- Master Boot Record
+* How It Works -- DOS Floppy Boot Sector
+* How It Works -- OS2 Boot Sector
+* How It Works -- Partition Tables
+
+
+Introduction (READ THIS!)
+-------------------------
+
+This is very technical. Please read carefully. There is lots of
+information here that can sound confusing the first time you read
+it.
+
+Why is an understanding of how a BIOS works so important? The
+basic reason is that the information returned by INT 13H AH=08H
+is used by FDISK, it is used in the partition table entries
+within a partition record (like the Master Boot Record) that are
+created by FDISK, and it is used by the small boot program that
+FDISK places into the Master Boot Record. The information
+returned by INT 13H AH=08H is in cylinder/head/sector (CHS)
+format -- it is not in LBA format. The boot processing done by
+your computer's BIOS (INT 19H and INT 13H) is all CHS based.
+
+Read this so that you are not confused by all the false
+information going around that says "LBA solves the >528MB
+problem".
+
+Read this so that you understand the possible data integrity
+problem that a WD EIDE type BIOS creates. Any BIOS that has a
+"LBA mode" in the BIOS setup could be a WD EIDE BIOS. Be very
+careful and NEVER chage the "LBA mode" setting after you have
+partitioned and installed your software.
+
+History
+-------
+
+Changes between this version and the preceeding version are
+marked by "!" at left margin of the first line of a changed
+or new paragraph.
+
+Version 4 -- BIOS Types 8 and 10 updated.
+
+Version 3 -- New BIOS types found and added to this list. More
+ detailed information is listed for each BIOS type. A section
+ describing CHS translation was added.
+
+Version 2 -- A rewrite of version 1 adding BIOS types not
+ included in version 1.
+
+Version 1 -- First attempt to classify the BIOS types and
+ describe what each does or does not do.
+
+Definitions
+-----------
+
+* 528MB - The maximun drive capacity that is supported by 1024
+ cylinders, 16 heads and 63 sectors (1024x16x63x512). This
+ is the limit for CHS addressing in the original IBM PC/XT
+ and IBM PC/AT INT 13H BIOS.
+
+* 8GB - The maximum drive capacity that can be supported by 1024
+ cylinders, 256 heads and 63 sectors (1024x256x63x512). This
+ is the limit for the BIOS INT 13H AH=0xH calls.
+
+* ATA - AT Attachment -- The real name of what is widely known
+ as IDE.
+
+* CE Cylinder - Customer Engineering cylinder. This is the
+ last cylinder in P-CHS mode. IBM has always reserved this
+ cylinder for use of disk diagnostic programs. Many BIOS do
+ not account for it correctly. It is of questionable value
+ these days and probably should be considered obsolete.
+ However, since there is no industry wide agreement, beware.
+ There is no CE Cylinder reserved in the L-CHS address. Also
+ beware of diagnostic programs that don't realize they are
+ operating in L-CHS mode and think that the last L-CHS cylinder
+ is the CE Cylinder.
+
+* CHS - Cylinder/Head/Sector. This is the traditional way to
+ address sectors on a disk. There are at least two types
+ of CHS addressing: the CHS that is used at the INT 13H
+ interface and the CHS that is used at the ATA device
+ interface. In the MFM/RLL/ESDI and early ATA days the CHS
+ used at the INT 13H interface was the same as the CHS used at
+ the device interface.
+
+ Today we have CHS translating BIOS types that can use one CHS
+ at the INT 13H interface and a different CHS at the device
+ interface. These two types of CHS will be called the logical
+ CHS or L-CHS and the physical CHS or P-CHS in this document.
+ L-CHS is the CHS used at the INT 13H interface and P-CHS is
+ the CHS used at the device interface.
+
+ The L-CHS used at the INT 13 interface allows up to 256 heads,
+ up to 1024 cylinders and up to 63 sectors. This allows
+ support of up to 8GB drives. This scheme started with either
+ ESDI or SCSI adapters many years ago.
+
+ The P-CHS used at the device interface allows up to 16 heads
+ up to 65535 cylinders, and up to 63 sectors. This allows
+ access to 2^28 sectors (136GB) on an ATA device. When a P-CHS
+ is used at the INT 13H interface it is limited to 1024
+ cylinders, 16 heads and 63 sectors. This is where the old
+ 528MB limit originated.
+
+ ATA devices may also support LBA at the device interface. LBA
+ allows access to approximately 2^28 sectors (137GB) on an ATA
+ device.
+
+ A SCSI host adapter can convert a L-CHS directly to an LBA
+ used in the SCSI read/write commands. On a PC today, SCSI is
+ also limited to 8GB when CHS addressing is used at the INT 13H
+ interface.
+
+* EDPT - Enhanced fixed Disk Parameter Table -- This table
+ returns additional information for BIOS drive numbers 80H and
+ 81H. The EDPT for BIOS drive 80H is pointed to by INT 41H.
+ The EDPT for BIOS drive 81H is pointed to by INT 46H. The
+ EDPT is a fixed disk parameter table with an AxH signature
+ byte. This table format returns two sets of CHS information.
+ One set is the L-CHS and is probably the same as returned by
+ INT 13H AH=08H. The other set is the P-CHS used at the drive
+ interface. This type of table allows drives with >1024
+ cylinders or drives >528MB to be supported. The translated
+ CHS will have <=1024 cylinders and (probably) >16 heads. The
+ CHS used at the drive interface will have >1024 cylinders and
+ <=16 heads. It is unclear how the IBM defined CE cylinder is
+ accounted for in such a table. Compaq probably gets the
+ credit for the original definition of this type of table.
+
+* FDPT - Fixed Disk Parameter Table - This table returns
+ additional information for BIOS drive numbers 80H and 81H.
+ The FDPT for BIOS drive 80H is pointed to by INT 41H. The
+ FDPT for BIOS drive 81H is pointed to by INT 46H. A FDPT does
+ not have a AxH signature byte. This table format returns a
+ single set of CHS information. The L-CHS information returned
+ by this table is probably the same as the P-CHS and is also
+ probably the same as the L-CHS returned by INT 13H AH=08H.
+ However, not all BIOS properly account for the IBM defined CE
+ cylinder and this can cause a one or two cylinder difference
+ between the number of cylinders returned in the AH=08H data
+ and the FDPT data. IBM gets the credit for the original
+ definition of this type of table.
+
+* LBA - Logical Block Address. Another way of addressing
+ sectors that uses a simple numbering scheme starting with zero
+ as the address of the first sector on a device. The ATA
+ standard requires that cylinder 0, head 0, sector 1 address
+ the same sector as addressed by LBA 0. LBA addressing can be
+ used at the ATA interface if the ATA device supports it. LBA
+ addressing is also used at the INT 13H interface by the AH=4xH
+ read/write calls.
+
+* L-CHS -- Logical CHS. The CHS used at the INT 13H interface by
+ the AH=0xH calls. See CHS above.
+
+* MBR - Master Boot Record (also known as a partition table) -
+ The sector located at cylinder 0 head 0 sector 1 (or LBA 0).
+ This sector is created by an "FDISK" utility program. The MBR
+ may be the only partition table sector or the MBR can be the
+ first of multiple partition table sectors that form a linked
+ list. A partition table entry can describe the starting and
+ ending sector addresses of a partition (also known as a
+ logical volume or a logical drive) in both L-CHS and LBA form.
+ Partition table entries use the L-CHS returned by INT 13H
+ AH=08H. Older FDISK programs may not compute valid LBA
+ values.
+
+* OS - Operating System.
+
+* P-CHS -- Physical CHS. The CHS used at the ATA device
+ interface. This CHS is also used at the INT 13H interface by
+ older BIOS's that do not support >1024 cylinders or >528MB.
+ See CHS above.
+
+Background and Assumptions
+--------------------------
+
+First, please note that this is written with the OS implementor
+in mind and that I am talking about the possible BIOS types as
+seen by an OS during its hardware configuration search.
+
+It is very important that you not be confused by all the
+misinformation going around these days. All OS's that want to be
+co-resident with another OS (and that is all of the PC based OS's
+that I know of) MUST use INT 13H to determine the capacity of a
+hard disk. And that capacity information MUST be determined in
+L-CHS mode. Why is this? Because: 1) FDISK and the partition
+tables are really L-CHS based, and 2) MS/PC DOS uses INT 13H
+AH=02H and AH=03H to read and write the disk and these BIOS calls
+are L-CHS based. The boot processing done by the BIOS is all
+L-CHS based. During the boot processing, all of the disk read
+accesses are done in L-CHS mode via INT 13H and this includes
+loading the first of the OS's kernel code or boot manager's code.
+
+Second, because there can be multiple BIOS types in any one
+system, each drive may be under the control of a different type
+of BIOS. For example, drive 80H (the first hard drive) could be
+controlled by the original system BIOS, drive 81H (the second
+drive) could be controlled by a option ROM BIOS and drive 82H
+(the third drive) could be controlled by a software driver.
+Also, be aware that each drive could be a different type, for
+example, drive 80H could be an MFM drive, drive 81H could be an
+ATA drive, drive 82H could be a SCSI drive.
+
+Third, not all OS's understand or use BIOS drive numbers greater
+than 81H. Even if there is INT 13H support for drives 82H or
+greater, the OS may not use that support.
+
+Fourth, the BIOS INT 13H configuration calls are:
+
+* AH=08H, Get Drive Parameters -- This call is restricted to
+ drives up to 528MB without CHS translation and to drives up to
+ 8GB with CHS translation. For older BIOS with no support for
+ >1024 cylinders or >528MB, this call returns the same CHS as
+ is used at the ATA interface (the P-CHS). For newer BIOS's
+ that do support >1024 cylinders or >528MB, this call returns a
+ translated CHS (the L-CHS). The CHS returned by this call is
+ used by FDISK to build partition records.
+
+* AH=41H, Get BIOS Extensions Support -- This call is used to
+ determine if the IBM/Microsoft Extensions or if the Phoenix
+ Enhanced INT 13H calls are supported for the BIOS drive
+ number.
+
+* AH=48H, Extended Get Drive Parameters -- This call is used to
+ determine the CHS geometries, LBA information and other data
+ about the BIOS drive number.
+
+* the FDPT or EDPT -- While not actually a call, but instead a
+ data area, the FDPT or EDPT can return additional information
+ about a drive.
+
+* other tables -- The IBM/Microsoft extensions provide a pointer
+ to a drive parameter table via INT 13H AH=48H. The Phoenix
+ enhancement provides a pointer to a drive parameter table
+ extension via INT 13H AH=48H. These tables are NOT the same
+ as the FDPT or EDPT.
+
+Note: The INT 13H AH=4xH calls duplicate the older AH=0xH calls
+but use a different parameter passing structure. This new
+structure allows support of drives with up to 2^64 sectors
+(really BIG drives). While at the INT 13H interface the AH=4xH
+calls are LBA based, these calls do NOT require that the drive
+support LBA addressing.
+
+CHS Translation Algorithms
+--------------------------
+
+NOTE: Before you send me email about this, read this entire
+ section. Thanks!
+
+As you read this, don't forget that all of the boot processing
+done by the system BIOS via INT 19H and INT 13H use only the INT
+13H AH=0xH calls and that all of this processing is done in CHS
+mode.
+
+First, lets review all the different ways a BIOS can be called
+to perform read/write operations and the conversions that a BIOS
+must support.
+
+! * An old BIOS (like BIOS type 1 below) does no CHS translation
+ and does not use LBA. It only supports the AH=0xH calls:
+
+ INT 13H (L-CHS == P-CHS) ATA
+ AH=0xH --------------------------------> device
+ (L-CHS) (P-CHS)
+
+* A newer BIOS may support CHS translation and it may support
+ LBA at the ATA interface:
+
+ INT 13H L-CHS ATA
+ AH=0xH --+--> to --+----------------> device
+ (L-CHS) | P-CHS | (P-CHS)
+ | |
+ | | P-CHS
+ | +--> to --+
+ | LBA |
+ | |
+ | L-CHS | ATA
+ +--> to -----------------+---> device
+ LBA (LBA)
+
+* A really new BIOS may also support the AH=4xH in addtion to
+ the older AH\0xH calls. This BIOS must support all possible
+ combinations of CHS and LBA at both the INT 13H and ATA
+ interfaces:
+
+ INT 13H ATA
+ AH=4xH --+-----------------------------> device
+ (LBA) | (LBA)
+ |
+ | LBA
+ +--> to ---------------+
+ P-CHS |
+ |
+ INT 13H L-CHS | ATA
+ AH=0xH --+--> to --+------------+---> device
+ (L-CHS) | P-CHS | (P-CHS)
+ | |
+ | | P-CHS
+ | +--> to --+
+ | LBA |
+ | |
+ | L-CHS | ATA
+ +--> to -----------------+---> device
+ LBA (LBA)
+
+You would think there is only one L-CHS to P-CHS translation
+algorithm, only one L-CHS to LBA translation algorithm and only
+one P-CHS to LBA translation algorithm. But this is not so.
+Why? Because there is no document that standardizes such an
+algorithm. You can not rely on all BIOS's and OS's to do these
+translations the same way.
+
+The following explains what is widely accepted as the
+"correct" algorithms.
+
+An ATA disk must implement both CHS and LBA addressing and
+must at any given time support only one P-CHS at the device
+interface. And, the drive must maintain a strick relationship
+between the sector addressing in CHS mode and LBA mode. Quoting
+the ATA-2 document:
+
+ LBA = ( (cylinder * heads_per_cylinder + heads )
+ * sectors_per_track ) + sector - 1
+
+ where heads_per_cylinder and sectors_per_track are the current
+ translation mode values.
+
+This algorithm can also be used by a BIOS or an OS to convert
+a L-CHS to an LBA as we'll see below.
+
+This algorithm can be reversed such that an LBA can be
+converted to a CHS:
+
+ cylinder = LBA / (heads_per_cylinder * sectors_per_track)
+ temp = LBA % (heads_per_cylinder * sectors_per_track)
+ head = temp / sectors_per_track
+ sector = temp % sectors_per_track + 1
+
+While most OS's compute disk addresses in an LBA scheme, an OS
+like DOS must convert that LBA to a CHS in order to call INT 13H.
+
+Technically an INT 13H should follow this process when
+converting an L-CHS to a P-CHS:
+
+ 1) convert the L-CHS to an LBA,
+ 2) convert the LBA to a P-CHS,
+
+If an LBA is required at the ATA interface, then this third
+step is needed:
+
+ 3) convert the P-CHS to an LBA.
+
+All of these conversions are done by normal arithmetic.
+
+However, while this is the technically correct way to do
+things, certain short cuts can be taken. It is possible to
+convert an L-CHS directly to a P-CHS using bit a bit shifting
+algorithm. This combines steps 1 and 2. And, if the ATA device
+being used supports LBA, steps 2 and 3 are not needed. The LBA
+value produced in step 1 is the same as the LBA value produced in
+step 3.
+
+AN EXAMPLE
+
+Lets look at an example. Lets say that the L-CHS is 1000
+cylinders 10 heads and 50 sectors, the P-CHS is 2000 cylinders, 5
+heads and 50 sectors. Lets say we want to access the sector at
+L-CHS 2,4,3.
+
+* step 1 converts the L-CHS to an LBA,
+
+ lba = 1202 = ( ( 2 * 10 + 4 ) * 50 ) + 3 - 1
+
+* step 2 converts the LBA to the P-CHS,
+
+ cylinder = 4 = ( 1202 / ( 5 * 50 )
+ temp = 202 = ( 1202 % ( 5 * 50 ) )
+ head = 4 = ( 202 / 50 )
+ sector = 3 = ( 202 % 50 ) + 1
+
+* step 3 converts the P-CHS to an LBA,
+
+ lba = 1202 = ( ( 4 * 5 + 4 ) * 50 ) + 3 - 1
+
+Most BIOS (or OS) software is not going to do all of this to
+convert an address. Most will use some other algorithm. There
+are many such algorithms.
+
+BIT SHIFTING INSTEAD
+
+If the L-CHS is produced from the P-CHS by 1) dividing the
+P-CHS cylinders by N, and 2) multiplying the P-CHS heads by N,
+where N is 2, 4, 8, ..., then this bit shifting algorithm can be
+used and N becomes a bit shift value. This is the most common
+way to make the P-CHS geometry of a >528MB drive fit the INT 13H
+L-CHS rules. Plus this algorithm maintains the same sector
+ordering as the more complex algorithm above. Note the
+following:
+
+ Lcylinder = L-CHS cylinder being accessed
+ Lhead = L-CHS head being accessed
+ Lsector = L-CHS sector being accessed
+
+ Pcylinder = the P-CHS cylinder being accessed
+ Phead = the P-CHS head being accessed
+ Psector = P-CHS sector being accessed
+
+ NPH = is the number of heads in the P-CHS
+ N = 2, 4, 8, ..., the bit shift value
+
+The algorithm, which can be implemented using bit shifting
+instead of multiply and divide operations is:
+
+ Pcylinder = ( Lcylinder * N ) + ( Lhead / NPH );
+ Phead = ( Lhead % NPH );
+ Psector = Lsector;
+
+A BIT SHIFTING EXAMPLE
+
+Lets apply this to our example above (L-CHS = 1000,10,50 and
+P-CHS = 2000, 5, 50) and access the same sector at at L-CHS
+2,4,3.
+
+ Pcylinder = 4 = ( 2 * 2 ) + ( 4 / 5 )
+ Phead = 4 = ( 4 % 5 )
+ Psector = 3 = 3
+
+As you can see, this produces the same P-CHS as the more
+complex method above.
+
+SO WHAT IS THE PROBLEM?
+
+The basic problem is that there is no requirement that a CHS
+translating BIOS followed these rules. There are many other
+algorithms that can be implemented to perform a similar function.
+Today, there are at least two popular implementions: the Phoenix
+implementation (described above) and the non-Phoenix
+implementations.
+
+SO WHY IS THIS A PROBLEM IF IT IS HIDDEN INSIDE THE BIOS?
+
+Because a protected mode OS that does not want to use INT 13H
+must implement the same CHS translation algorithm. If it
+doesn't, your data gets scrambled.
+
+WHY USE CHS AT ALL?
+
+In the perfect world of tomorrow, maybe only LBA will be used.
+But today we are faced with the following problems:
+
+* Some drives >528MB don't implement LBA.
+
+* Some drives are optimized for CHS and may have lower
+ performance when given commands in LBA mode. Don't forget
+ that LBA is something new for the ATA disk designers who have
+ worked very hard for many years to optimize CHS address
+ handling. And not all drive designs require the use of LBA
+ internally.
+
+* The L-CHS to LBA conversion is more complex and slower than
+ the bit shifting L-CHS to P-CHS conversion.
+
+* DOS, FDISK and the MBR are still CHS based -- they use the
+ CHS returned by INT 13H AH=08H. Any OS that can be installed
+ on the same disk with DOS must understand CHS addressing.
+
+* The BIOS boot processing and loading of the first OS kernel
+ code is done in CHS mode -- the CHS returned by INT 13H AH=08H
+ is used.
+
+* Microsoft has said that their OS's will not use any disk
+ capacity that can not also be accessed by INT 13H AH=0xH.
+
+These are difficult problems to overcome in today's industry
+environment. The result: chaos.
+
+DANGER TO YOUR DATA!
+
+See the description of BIOS Type 7 below to understand why a
+WD EIDE BIOS is so dangerous to your data.
+
+
+The BIOS Types
+--------------
+
+I assume the following:
+
+a) All BIOS INT 13H support has been installed by the time the OS
+ starts its boot processing. I'm don't plan to cover what
+ could happen to INT 13H once the OS starts loading its own
+ device drivers.
+
+b) Drives supported by INT 13H are numbered sequentially starting
+ with drive number 80H (80H-FFH are hard drives, 00-7FH are
+ floppy drives).
+
+And remember, any time a P-CHS exists it may or may not account
+ for the CE Cylinder properly.
+
+I have identified the following types of BIOS INT 13H support as
+seen by an OS during its boot time hardware configuration
+determination:
+
+BIOS Type 1
+
+ Origin: Original IBM PC/XT.
+
+ BIOS call support: INT 13H AH=0xH and FDPT for BIOS drives
+ 80H and 81H. There is no CHS translation. INT 13H AH=08H
+ returns the P-CHS. The FDPT should contain the same P-CHS.
+
+ Description: Supports up to 528MB from a table of drive
+ descriptions in BIOS ROM. No support for >1024 cylinders or
+ drives >528MB or LBA.
+
+ Support issues: For >1024 cylinders or >528MB support, either
+ an option ROM with an INT 13H replacement (see BIOS types 4-7)
+ -or- a software driver (see BIOS type 8) must be added to the
+ system.
+
+BIOS Type 2
+
+ Origin: Unknown, but first appeared on systems having BIOS
+ drive type table entries defining >1024 cylinders. Rumored to
+ have originated at the request of Novell or SCO.
+
+ BIOS call support: INT 13H AH=0xH and FDPT for BIOS drives
+ 80H and 81H. INT 13H AH=08H should return a L-CHS with the
+ cylinder value limited to 1024. Beware, many BIOS perform
+ a logical AND on the cylinder value. A correct BIOS will
+ limit the cylinder value as follows:
+
+ cylinder = cylinder > 1024 ? 1024 : cylinder;
+
+ An incorrect BIOS will limit the cylinder value as follows
+ (this implementation turns a 540MB drive into a 12MB drive!):
+
+ cylinder = cylinder & 0x03ff;
+
+ The FDPT will return a P-CHS that has the full cylinder
+ value.
+
+ Description: For BIOS drive numbers 80H and 81H, this BIOS
+ type supports >1024 cylinders or >528MB without using a
+ translated CHS in the FDPT. INT 13H AH=08H truncates
+ cylinders to 1024 (beware of buggy implementations). The FDPT
+ can show >1024 cylinders thereby allowing an OS to support
+ drives >528MB. May convert the L-CHS or P-CHS directly to an
+ LBA if the ATA device supports LBA.
+
+ Support issues: Actual support of >1024 cylinders is OS
+ specific -- some OS's may be able to place OS specific
+ partitions spanning or beyond cylinder 1024. Usually all OS
+ boot code must be within first 1024 cylinders. The FDISK
+ program of an OS that supports such partitions uses an OS
+ specific partition table entry format to identify these
+ paritions. There does not appear to be a standard (de facto
+ or otherwise) for this unusual partition table entry.
+ Apparently one method is to place -1 into the CHS fields and
+ use the LBA fields to describe the location of the partition.
+ This DOES NOT require the drive to support LBA addressing.
+ Using an LBA in the partition table entry is just a trick to
+ get around the CHS limits in the partition table entry. It is
+ unclear if such a partition table entry will be ignored by an
+ OS that does not understand what it is. For an OS that does
+ not support such partitions, either an option ROM with an INT
+ 13H replacement (see BIOS types 4-7) -or- a software driver
+ (see BIOS type 8) must be added to the system.
+
+ Note: OS/2 can place HPFS partitions and Linux can place
+ Linux partitions beyond or spanning cylinder 1024. (Anyone
+ know of other systems that can do the same?)
+
+BIOS Type 3
+
+ Origin: Unknown, but first appeared on systems having BIOS
+ drive type table entires defining >1024 cylinders. Rumored to
+ have originated at the request of Novell or SCO.
+
+ BIOS call support: INT 13H AH=0xH and FDPT for BIOS drives
+ 80H and 81H. INT 13H AH=08H can return an L-CHS with more
+ than 1024 cylinders.
+
+ Description: This BIOS is like type 2 above but it allows up
+ to 4096 cylinders (12 cylinder bits). It does this in the INT
+ 13H AH=0xH calls by placing two most significant cylinder bits
+ (bits 11 and 10) into the upper two bits of the head number
+ (bits 7 and 6).
+
+ Support issues: Identification of such a BIOS is difficult.
+ As long as the drive(s) supported by this type of BIOS have
+ <1024 cylinders this BIOS looks like a type 2 BIOS because INT
+ 13H AH=08H should return zero data in bits 7 and 6 of the head
+ information. If INT 13H AH=08H returns non zero data in bits
+ 7 and 6 of the head information, perhaps it can be assumed
+ that this is a type 3 BIOS. For more normal support of >1024
+ cylinders or >528MB, either an option ROM with an INT 13H
+ replacement (see BIOS types 4-7) -or- a software driver (see
+ BIOS type 8) must be added to the system.
+
+ Note: Apparently this BIOS type is no longer produced by any
+ BIOS vendor.
+
+BIOS Type 4
+
+ Origin: Compaq. Probably first appeared in systems with ESDI
+ drives having >1024 cylinders.
+
+ BIOS call support: INT 13H AH=0xH and EDPT for BIOS drives
+ 80H and 81H. If the drive has <1024 cylinders, INT 13H AH=08H
+ returns the P-CHS and a FDPT is built. If the drive has >1024
+ cylinders, INT 13H AH=08H returns an L-CHS and an EDPT is
+ built.
+
+ Description: Looks like a type 2 BIOS when an FDPT is built.
+ Uses CHS translation when an EDPT is used. May convert the
+ L-CHS directly to an LBA if the ATA device supports LBA.
+
+ Support issues: This BIOS type may support up to four drives
+ with a EDPT (or FDPT) for BIOS drive numbers 82H and 83H
+ located in memory following the EDPT (or FDPT) for drive 80H.
+ Different CHS translation algorithms may be used by the BIOS
+ and an OS.
+
+BIOS Type 5
+
+ Origin: The IBM/Microsoft BIOS Extensions document. For many
+ years this document was marked "confidential" so it did not
+ get wide spread distribution.
+
+ BIOS call support: INT 13H AH=0xH, AH=4xH and EDPT for BIOS
+ drives 80H and 81H. INT 13H AH=08H returns an L-CHS. INT 13H
+ AH=41H and AH=48H should be used to get P-CHS configuration.
+ The FDPT/EDPT should not be used. In some implementations the
+ FDPT/EDPT may not exist.
+
+ Description: A BIOS that supports very large drives (>1024
+ cylinders, >528MB, actually >8GB), and supports the INT 13H
+ AH=4xH read/write functions. The AH=4xH calls use LBA
+ addressing and support drives with up to 2^64 sectors. These
+ calls do NOT require that a drive support LBA at the drive
+ interface. INT 13H AH=48H describes the L-CHS used at the INT
+ 13 interface and the P-CHS or LBA used at the drive interface.
+ This BIOS supports the INT 13 AH=0xH calls the same as a BIOS
+ type 4.
+
+ Support issues: While the INT 13H AH=4xH calls are well
+ defined, they are not implemented in many systems shipping
+ today. Currently undefined is how such a BIOS should respond
+ to INT 13H AH=08H calls for a drive that is >8GB. Different
+ CHS translation algorithms may be used by the BIOS and an OS.
+
+ Note: Support of LBA at the drive interface may be automatic
+ or may be under user control via a BIOS setup option. Use of
+ LBA at the drive interface does not change the operation of
+ the INT 13 interface.
+
+BIOS Type 6
+
+ Origin: The Phoenix Enhanced Disk Drive Specification.
+
+ BIOS call support: INT 13H AH=0xH, AH=4xH and EDPT for BIOS
+ drives 80H and 81H. INT 13H AH=08H returns an L-CHS. INT 13H
+ AH=41H and AH=48H should be used to get P-CHS configuration.
+ INT 13H AH=48H returns the address of the Phoenix defined
+ "FDPT Extension" table.
+
+ Description: A BIOS that supports very large drives (>1024
+ cylinders, >528MB, actually >8GB), and supports the INT 13H
+ AH=4xH read/write functions. The AH=4xH calls use LBA
+ addressing and support drives with up to 2^64 sectors. These
+ calls do NOT require that a drive support LBA at the drive
+ interface. INT 13H AH=48H describes the L-CHS used at the INT
+ 13 interface and the P-CHS or LBA used at the drive interface.
+ This BIOS supports the INT 13 AH=0xH calls the same as a BIOS
+ type 4. The INT 13H AH=48H call returns additional information
+ such as host adapter addresses, DMA support, LBA support, etc,
+ in the Phoenix defined "FDPT Extension" table.
+
+ Phoenix says this this BIOS need not support the INT 13H
+ AH=4xH read/write calls but this BIOS is really an
+ extension/enhancement of the original IBM/MS BIOS so most
+ implementations will probably support the full set of INT 13H
+ AH=4xH calls.
+
+ Support issues: Currently undefined is how such a BIOS should
+ respond to INT 13H AH=08H calls for a drive that is >8GB.
+ Different CHS translation algorithms may be used by the BIOS
+ and an OS.
+
+ Note: Support of LBA at the drive interface may be automatic
+ or may be under user control via a BIOS setup option. Use of
+ LBA at the drive interface does not change the operation of
+ the INT 13 interface.
+
+BIOS Type 7
+
+ Origin: Described in the Western Digital Enhanced IDE
+ Implementation Guide.
+
+ BIOS call support: INT 13H AH=0xH and FDPT or EDPT for BIOS
+ drives 80H and 81H. An EDPT with a L-CHS of 16 heads and 63
+ sectors is built when "LBA mode" is enabled. An FDPT is built
+ when "LBA mode" is disabled.
+
+ Description: Supports >1024 cylinders or >528MB using a EDPT
+ with a translated CHS *** BUT ONLY IF *** the user requests
+ "LBA mode" in the BIOS setup *** AND *** the drive supports
+ LBA. As long as "LBA mode" is enabled, CHS translation is
+ enabled using a L-CHS with <=1024 cylinders, 16, 32, 64, ...,
+ heads and 63 sectors. Disk read/write commands are issued in
+ LBA mode at the ATA interface but other commands are issued in
+ P-CHS mode. Because the L-CHS is determined by table lookup
+ based on total drive capacity and not by a multiply/divide of
+ the P-CHS cylinder and head values, it may not be possible to
+ use the simple (and faster) bit shifting L-CHS to P-CHS
+ algorithms.
+
+ When "LBA mode" is disabled, this BIOS looks like a BIOS type
+ 2 with an FDPT. The L-CHS used is taken either from the BIOS
+ drive type table or from the device's Identify Device data.
+ This L-CHS can be very different from the L-CHS returned when
+ "LBA mode" is enabled.
+
+ This BIOS may support FDPT/EDPT for up to four drives in the
+ same manner as described in BIOS type 4.
+
+ The basic problem with this BIOS is that the CHS returned by
+ INT 13H AH=08H changes because of a change in the "LBA mode"
+ setting in the BIOS setup. This should not happen. This use
+ or non-use of LBA at the ATA interface should have no effect
+ on the CHS returned by INT 13H AH=08H. This is the only BIOS
+ type know to have this problem.
+
+ Support issues: If the user changes the "LBA mode" setting in
+ BIOS setup, INT 13H AH=08H and the FDPT/EDPT change
+ which may cause *** DATA CORRUPTION ***. The user should be
+ warned to not change the "LBA mode" setting in BIOS setup once
+ the drive has been partitioned and software installed.
+ Different CHS translation algorithms may be used by the BIOS
+ and an OS.
+
+BIOS Type 8
+
+ Origin: Unknown. Perhaps Ontrack's Disk Manager was the
+ first of these software drivers. Another example of such a
+ driver is Micro House's EZ Drive.
+
+ BIOS call support: Unknown (anyone care to help out here?).
+ Mostly likely only INT 13H AH=0xH are support. Probably a
+ FDPT or EDPT exists for drives 80H and 81H.
+
+! Description: A software driver that "hides" in the MBR such
+ that it is loaded into system memory before any OS boot
+ processing starts. These drivers can have up to three parts:
+ a part that hides in the MBR, a part that hides in the
+ remaining sectors of cylinder 0, head 0, and an OS device
+ driver. The part in the MBR loads the second part of the
+ driver from cylinder 0 head 0. The second part provides a
+ replacement for INT 13H that enables CHS translation for at
+ least the boot drive. Usually the boot drive is defined in
+ CMOS setup as a type 1 or 2 (5MB or 10MB drive). Once the
+ second part of the driver is loaded, this definition is
+ changed to describe the true capacity of the drive and INT 13H
+ is replaced by the driver's version of INT 13H that does CHS
+ translation. In some cases the third part, an OS specific
+ device driver, must be loaded to enable CHS translation for
+ devices other than the boot device.
+
+! I don't know the details of how these drivers respond to INT
+ 13H AH=08H or how they set up drive parameter tables (anyone
+ care to help out here?). Some of these drivers convert the
+ L-CHS to an LBA, then they add a small number to the LBA and
+ finally they convert the LBA to a P-CHS. This in effect skips
+ over some sectors at the front of the disk.
+
+ Support issues: Several identified -- Some OS installation
+ programs will remove or overlay these drivers; some of these
+ drivers do not perform CHS translation using the same
+ algorithms used by the other BIOS types; special OS device
+ drivers may be required in order to use these software drivers
+ For example, under MS Windows the standard FastDisk driver
+ (the 32-bit disk access driver) must be replaced by a driver
+ that understands the Ontrack, Micro House, etc, version of INT
+ 13H. Different CHS translation algorithms may be used by the
+ driver and an OS.
+
+! The hard disk vendors have been shipping these drivers with
+ their drives over 528MB during the last year and they have
+ been ignoring the statements of Microsoft and IBM that these
+ drivers would not be supported in future OS's. Now it appears
+ that both Microsoft and IBM are in a panic trying to figure
+ out how to support some of these drivers in WinNT, Win95 and
+ OS/2. It is unclear what the outcome of this will be at this
+ time.
+
+! NOTE: THIS IS NOT A PRODUCT ENDORSEMENT! An alternate
+ solution for an older ISA system is one of the BIOS
+ replacement cards. This cards have a BIOS option ROM. AMI
+ makes such a card called the "Disk Extender". This card
+ replaces the motherboard's INT 13H BIOS with a INT 13H BIOS
+ that does some form of CHS translation. Another solution for
+ older VL-Bus systems is an ATA-2 (EIDE) type host adapter card
+ that provides a option ROM with an INT 13H replacement.
+
+BIOS Type 9
+
+ Origin: SCSI host adapters.
+
+ BIOS call support: Probably INT 13H AH=0xH and FDPT for BIOS
+ drives 80H and 81H, perhaps INT 13H AH=4xH.
+
+ Description: Most SCSI host adapters contain an option ROM
+ that enables INT 13 support for the attached SCSI hard drives.
+ It is possible to have more than one SCSI host adapter, each
+ with its own option ROM. The CHS used at the INT 13H
+ interface is converted to the LBA that is used in the SCSI
+ commands. INT 13H AH=08H returns a CHS. This CHS will have
+ <=1024 cylinders, <=256 heads and <=63 sectors. The FDPT
+ probably will exist for SCSI drives with BIOS drive numbers of
+ 80H and 81H and probably indicates the same CHS as that
+ returned by INT 13H AH=08H. Even though the CHS used at the
+ INT 13H interface looks like a translated CHS, there is no
+ need to use a EDPT since there is no CHS-to-CHS translation
+ used. Other BIOS calls (most likely host adapter specific)
+ must be used to determine other information about the host
+ adapter or the drives.
+
+ The INT 13H AH=4xH calls can be used to get beyond 8GB but
+ since there is little support for these calls in today's OS's,
+ there are probably few SCSI host adapters that support these
+ newer INT 13H calls.
+
+ Support issues: Some SCSI host adapters will not install
+ their option ROM if there are two INT 13H devices previously
+ installed by another INT 13H BIOS (for example, two
+ MFM/RLL/ESDI/ATA drives). Other SCSI adapters will install
+ their option ROM and use BIOS drive numbers greater than 81H.
+ Some older OS's don't understand or use BIOS drive numbers
+ greater than 81H. SCSI adapters are currently faced with the
+ >8GB drive problem.
+
+BIOS Type 10
+
+ Origin: A european system vendor.
+
+ BIOS call support: INT 13H AH=0xH and FDPT for BIOS drives
+ 80H and 81H.
+
+ Description: This BIOS supports drives >528MB but it does not
+ support CHS translation. It supports only ATA drives with LBA
+ capability. INT 13H AH=08H returns an L-CHS. The L-CHS is
+ converted directly to an LBA. The BIOS sets the ATA drive to
+ a P-CHS of 16 heads and 63 sectors using the Initialize Drive
+ Parameters command but it does not use this P-CHS at the ATA
+ interface.
+
+! Support issues: OS/2 will probably work with this BIOS as
+ long as the drive's power on default P-CHS mode uses 16 heads
+ and 63 sectors. Because there is no EDPT, OS/2 uses the ATA
+ Identify Device power on default P-CHS, described in
+ Identify Device words 1, 3 and 6 as the current P-CHS for the
+ drive. However, this may not represent the correct P-CHS. A
+ newer drive will have the its current P-CHS information in
+ Identify Device words 53-58 but for some reason OS/2 does not
+ use this information.
+
+/end of part 2 of 2/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//
diff --git a/etc/etc.i386/INSTALL.dbr b/etc/etc.i386/INSTALL.dbr
new file mode 100644
index 00000000000..1f0b5fcefa8
--- /dev/null
+++ b/etc/etc.i386/INSTALL.dbr
@@ -0,0 +1,467 @@
+ How It Works -- DOS Floppy Disk Boot Sector
+
+ Version 1a
+
+ by Hale Landis (landis@sugs.tware.com)
+
+
+THE "HOW IT WORKS" SERIES
+
+This is one of several How It Works documents. The series
+currently includes the following:
+
+* How It Works -- CHS Translation
+* How It Works -- Master Boot Record
+* How It Works -- DOS Floppy Boot Sector
+* How It Works -- OS2 Boot Sector
+* How It Works -- Partition Tables
+
+
+DOS FLOPPY DISK BOOT SECTOR
+
+This article is a disassembly of a floppy disk boot sector for a
+DOS floppy. The boot sector of a floppy disk is located at
+cylinder 0, head 0, sector 1. This sector is created by a floppy
+disk formating program, such as the DOS FORMAT program. The boot
+sector of a FAT hard disk partition has a similar layout and
+function. Basically a bootable FAT hard disk partition looks
+like a big floppy during the early stages of the system's boot
+processing.
+
+At the completion of your system's Power On Self Test (POST), INT
+19 is called. Usually INT 19 tries to read a boot sector from
+the first floppy drive. If a boot sector is found on the floppy
+disk, the that boot sector is read into memory at location
+0000:7C00 and INT 19 jumps to memory location 0000:7C00.
+However, if no boot sector is found on the first floppy drive,
+INT 19 tries to read the MBR from the first hard drive. If an
+MBR is found it is read into memory at location 0000:7c00 and INT
+19 jumps to memory location 0000:7c00. The small program in the
+MBR will attempt to locate an active (bootable) partition in its
+partition table. If such a partition is found, the boot sector
+of that partition is read into memory at location 0000:7C00 and
+the MBR program jumps to memory location 0000:7C00. Each
+operating system has its own boot sector format. The small
+program in the boot sector must locate the first part of the
+operating system's kernel loader program (or perhaps the kernel
+itself or perhaps a "boot manager program") and read that into
+memory.
+
+INT 19 is also called when the CTRL-ALT-DEL keys are used. On
+most systems, CTRL-ALT-DEL causes an short version of the POST to
+be executed before INT 19 is called.
+
+=====
+
+Where stuff is:
+
+ The BIOS Parameter Block (BPB) starts at offset 0.
+ The boot sector program starts at offset 3e.
+ The messages issued by this program start at offset 19e.
+ The DOS hidden file names start at offset 1e6.
+ The boot sector signature is at offset 1fe.
+
+Here is a summary of what this thing does:
+
+1) Copy Diskette Parameter Table which is pointed to by INT 1E.
+2) Alter the copy of the Diskette Parameter Table.
+3) Alter INT 1E to point to altered Diskette Parameter Table.
+4) Do INT 13 AH=00, disk reset call.
+5) Compute sector address of root directory.
+6) Read first sector of root directory into 0000:0500.
+7) Confirm that first two directory entries are for IO.SYS
+ and MSDOS.SYS.
+8) Read first 3 sectors of IO.SYS into 0000:0700 (or 0070:0000).
+9) Leave some information in the registers and jump to
+ IO.SYS at 0070:0000.
+
+NOTE:
+
+ This program uses the CHS based INT 13H AH=02 to read the FAT
+ root directory and to read the IO.SYS file. If the drive is
+ >528MB, this CHS must be a translated CHS (or L-CHS, see my
+ BIOS TYPES document). Except for internal computations no
+ addresses in LBA form are used, another reason why LBA doesn't
+ solve the >528MB problem.
+
+=====
+
+Here is the entire sector in hex and ascii.
+
+OFFSET 0 1 2 3 4 5 6 7 8 9 A B C D E F *0123456789ABCDEF*
+000000 eb3c904d 53444f53 352e3000 02010100 *.<.MSDOS5.0.....*
+000010 02e00040 0bf00900 12000200 00000000 *...@............*
+000020 00000000 0000295a 5418264e 4f204e41 *......)ZT.&NO NA*
+000030 4d452020 20204641 54313220 2020fa33 *ME FAT12 .3*
+000040 c08ed0bc 007c1607 bb780036 c5371e56 *.....|...x.6.7.V*
+000050 1653bf3e 7cb90b00 fcf3a406 1fc645fe *.S.>|.........E.*
+000060 0f8b0e18 7c884df9 894702c7 073e7cfb *....|.M..G...>|.*
+000070 cd137279 33c03906 137c7408 8b0e137c *..ry3.9..|t....|*
+000080 890e207c a0107cf7 26167c03 061c7c13 *.. |..|.&.|...|.*
+000090 161e7c03 060e7c83 d200a350 7c891652 *..|...|....P|..R*
+0000a0 7ca3497c 89164b7c b82000f7 26117c8b *|.I|..K|. ..&.|.*
+0000b0 1e0b7c03 c348f7f3 0106497c 83164b7c *..|..H....I|..K|*
+0000c0 00bb0005 8b16527c a1507ce8 9200721d *......R|.P|...r.*
+0000d0 b001e8ac 0072168b fbb90b00 bee67df3 *.....r........}.*
+0000e0 a6750a8d 7f20b90b 00f3a674 18be9e7d *.u... .....t...}*
+0000f0 e85f0033 c0cd165e 1f8f048f 4402cd19 *._.3...^....D...*
+000100 585858eb e88b471a 48488a1e 0d7c32ff *XXX...G.HH...|2.*
+000110 f7e30306 497c1316 4b7cbb00 07b90300 *....I|..K|......*
+000120 505251e8 3a0072d8 b001e854 00595a58 *PRQ.:.r....T.YZX*
+000130 72bb0501 0083d200 031e0b7c e2e28a2e *r..........|....*
+000140 157c8a16 247c8b1e 497ca14b 7cea0000 *.|..$|..I|.K|...*
+000150 7000ac0a c07429b4 0ebb0700 cd10ebf2 *p....t).........*
+000160 3b16187c 7319f736 187cfec2 88164f7c *;..|s..6.|....O|*
+000170 33d2f736 1a7c8816 257ca34d 7cf8c3f9 *3..6.|..%|.M|...*
+000180 c3b4028b 164d7cb1 06d2e60a 364f7c8b *.....M|.....6O|.*
+000190 ca86e98a 16247c8a 36257ccd 13c30d0a *.....$|.6%|.....*
+0001a0 4e6f6e2d 53797374 656d2064 69736b20 *Non-System disk *
+0001b0 6f722064 69736b20 6572726f 720d0a52 *or disk error..R*
+0001c0 65706c61 63652061 6e642070 72657373 *eplace and press*
+0001d0 20616e79 206b6579 20776865 6e207265 * any key when re*
+0001e0 6164790d 0a00494f 20202020 20205359 *ady...IO SY*
+0001f0 534d5344 4f532020 20535953 000055aa *SMSDOS SYS..U.*
+
+=====
+
+The first 62 bytes of a boot sector are known as the BIOS
+Parameter Block (BPB). Here is the layout of the BPB fields
+and the values they are assigned in this boot sector:
+
+ db JMP instruction at 7c00 size 2 = eb3c
+ db NOP instruction 7c02 1 90
+ db OEMname 7c03 8 'MSDOS5.0'
+ dw bytesPerSector 7c0b 2 0200
+ db sectPerCluster 7c0d 1 01
+ dw reservedSectors 7c0e 2 0001
+ db numFAT 7c10 1 02
+ dw numRootDirEntries 7c11 2 00e0
+ dw numSectors 7c13 2 0b40 (ignore numSectorsHuge)
+ db mediaType 7c15 1 f0
+ dw numFATsectors 7c16 2 0009
+ dw sectorsPerTrack 7c18 2 0012
+ dw numHeads 7c1a 2 0002
+ dd numHiddenSectors 7c1c 4 00000000
+ dd numSectorsHuge 7c20 4 00000000
+ db driveNum 7c24 1 00
+ db reserved 7c25 1 00
+ db signature 7c26 1 29
+ dd volumeID 7c27 4 5a541826
+ db volumeLabel 7c2b 11 'NO NAME '
+ db fileSysType 7c36 8 'FAT12 '
+
+=====
+
+Here is the boot sector...
+
+The first 3 bytes of the BPB are JMP and NOP instructions.
+
+0000:7C00 EB3C JMP START
+0000:7C02 90 NOP
+
+Here is the rest of the BPB.
+
+0000:7C00 ......4d 53444f53 352e3000 02010100 * MSDOS5.0.....*
+0000:7C10 02e00040 0bf00900 12000200 00000000 *...@............*
+0000:7C20 00000000 0000295a 5418264e 4f204e41 *......)ZT.&NO NA*
+0000:7C30 4d452020 20204641 54313220 2020.... *ME FAT12 *
+
+Now pay attention here...
+
+ The 11 bytes starting at 0000:7c3e are immediately overlaid by
+ information copied from another part of memory. That
+ information is the Diskette Parameter Table. This data is
+ pointed to by INT 1E. This data is:
+
+ 7c3e = Step rate and head unload time.
+ 7c3f = Head load time and DMA mode flag.
+ 7c40 = Delay for motor turn off.
+ 7c41 = Bytes per sector.
+ 7c42 = Sectors per track.
+ 7c43 = Intersector gap length.
+ 7c44 = Data length.
+ 7c45 = Intersector gap length during format.
+ 7c46 = Format byte value.
+ 7c47 = Head settling time.
+ 7c48 = Delay until motor at normal speed.
+
+ The 11 bytes starting at 0000:7c49 are also overlaid by the
+ following data:
+
+ 7c49 - 7c4c = diskette sector address (as LBA)
+ of the data area.
+ 7c4d - 7c4e = cylinder number to read from.
+ 7c4f - 7c4f = sector number to read from.
+ 7c50 - 7c53 = diskette sector address (as LBA)
+ of the root directory.
+
+ START: START OF BOOT SECTOR PROGRAM
+
+0000:7C3E FA CLI interrupts off
+0000:7C3F 33C0 XOR AX,AX set AX to zero
+0000:7C41 8ED0 MOV SS,AX SS is now zero
+0000:7C43 BC007C MOV SP,7C00 SP is now 7c00
+0000:7C46 16 PUSH SS also set ES
+0000:7C47 07 POP ES to zero
+
+ The INT 1E vector is at 0000:0078.
+ Get the address that the vector points to
+ into the DS:SI registers.
+
+0000:7C48 BB7800 MOV BX,0078 BX is now 78
+0000:7C4B 36 SS:
+0000:7C4C C537 LDS SI,[BX] DS:SI is now [0:78]
+0000:7C4E 1E PUSH DS save DS:SI --
+0000:7C4F 56 PUSH SI saves param tbl addr
+0000:7C50 16 PUSH SS save SS:BX --
+0000:7C51 53 PUSH BX saves INT 1E address
+
+ Move the diskette param table to 0000:7c3e.
+
+0000:7C52 BF3E7C MOV DI,7C3E DI is address of START
+0000:7C55 B90B00 MOV CX,000B count is 11
+0000:7C58 FC CLD clear direction
+0000:7C59 F3 REPZ move the diskette param
+0000:7C5A A4 MOVSB table to 0000:7c3e
+0000:7C5B 06 PUSH ES also set DS
+0000:7C5C 1F POP DS to zero
+
+ Alter some of the diskette param table data.
+
+0000:7C5D C645FE0F MOV BYTE PTR [DI-02],0F change head settle time
+ at 0000:7c47
+0000:7C61 8B0E187C MOV CX,[7C18] sectors per track
+0000:7C65 884DF9 MOV [DI-07],CL save at 0000:7c42
+
+ Change INT 1E so that it points to the
+ altered Diskette param table at 0000:7c3e.
+
+0000:7C68 894702 MOV [BX+02],AX change INT 1E segment
+0000:7C6B C7073E7C MOV WORD PTR [BX],7C3E change INT 1E offset
+
+ Call INT 13 with AX=0000, disk reset, so
+ that the new diskette param table is used.
+
+0000:7C6F FB STI interrupts on
+0000:7C70 CD13 INT 13 do diskette reset call
+0000:7C72 7279 JB TALK jmp if any error
+
+ Detemine the starting sector address of
+ the root directory as an LBA.
+
+0000:7C74 33C0 XOR AX,AX AX is now zero
+0000:7C76 3906137C CMP [7C13],AX number sectros zero?
+0000:7C7A 7408 JZ SMALL_DISK yes
+0000:7C7C 8B0E137C MOV CX,[7C13] number of sectors
+0000:7C80 890E207C MOV [7C20],CX save in huge num sects
+
+ SMALL_DISK:
+
+0000:7C84 A0107C MOV AL,[7C10] number of FAT tables
+0000:7C87 F726167C MUL WORD PTR [7C16] number of fat sectors
+0000:7C8B 03061C7C ADD AX,[7C1C] number of hidden sectors
+0000:7C8F 13161E7C ADC DX,[7C1E] number of hidden sectors
+0000:7C93 03060E7C ADD AX,[7C0E] number of reserved sectors
+0000:7C97 83D200 ADC DX,+00 number of reserved sectors
+0000:7C9A A3507C MOV [7C50],AX save start addr
+0000:7C9D 8916527C MOV [7C52],DX of root dir (as LBA)
+0000:7CA1 A3497C MOV [7C49],AX save start addr
+0000:7CA4 89164B7C MOV [7C4B],DX of root dir (as LBA)
+
+ Determine sector address of first sector
+ in the data area as an LBA.
+
+0000:7CA8 B82000 MOV AX,0020 size of a dir entry (32)
+0000:7CAB F726117C MUL WORD PTR [7C11] number of root dir entries
+0000:7CAF 8B1E0B7C MOV BX,[7C0B] bytes per sector
+0000:7CB3 03C3 ADD AX,BX
+0000:7CB5 48 DEC AX
+0000:7CB6 F7F3 DIV BX
+0000:7CB8 0106497C ADD [7C49],AX add to start addr
+0000:7CBC 83164B7C00 ADC WORD PTR [7C4B],+00 of root dir (as LBA)
+
+ Read the first root dir sector into 0000:0500.
+
+0000:7CC1 BB0005 MOV BX,0500 addr to read into
+0000:7CC4 8B16527C MOV DX,[7C52] get start of address
+0000:7CC8 A1507C MOV AX,[7C50] of root dir (as LBA)
+0000:7CCB E89200 CALL CONVERT call conversion routine
+0000:7CCE 721D JB TALK jmp is any error
+0000:7CD0 B001 MOV AL,01 read 1 sector
+0000:7CD2 E8AC00 CALL READ_SECTORS read 1st root dir sector
+0000:7CD5 7216 JB TALK jmp if any error
+0000:7CD7 8BFB MOV DI,BX addr of 1st dir entry
+0000:7CD9 B90B00 MOV CX,000B count is 11
+0000:7CDC BEE67D MOV SI,7DE6 addr of file names
+0000:7CDF F3 REPZ is this "IO.SYS"?
+0000:7CE0 A6 CMPSB
+0000:7CE1 750A JNZ TALK no
+0000:7CE3 8D7F20 LEA DI,[BX+20] addr of next dir entry
+0000:7CE6 B90B00 MOV CX,000B count is 11
+0000:7CE9 F3 REPZ is this "MSDOS.SYS"?
+0000:7CEA A6 CMPSB
+0000:7CEB 7418 JZ FOUND_FILES they are equal
+
+ TALK:
+
+ Display "Non-System disk..." message,
+ wait for user to hit a key, restore
+ the INT 1E vector and then
+ call INT 19 to start boot processing
+ all over again.
+
+0000:7CED BE9E7D MOV SI,7D9E "Non-System disk..."
+0000:7CF0 E85F00 CALL MSG_LOOP display message
+0000:7CF3 33C0 XOR AX,AX INT 16 function
+0000:7CF5 CD16 INT 16 read keyboard
+0000:7CF7 5E POP SI get INT 1E vector's
+0000:7CF8 1F POP DS address
+0000:7CF9 8F04 POP [SI] restore the INT 1E
+0000:7CFB 8F4402 POP [SI+02] vector's data
+0000:7CFE CD19 INT 19 CALL INT 19 to try again
+
+ SETUP_TALK:
+
+0000:7D00 58 POP AX pop junk off stack
+0000:7D01 58 POP AX pop junk off stack
+0000:7D02 58 POP AX pop junk off stack
+0000:7D03 EBE8 JMP TALK now talk to the user
+
+ FOUND_FILES:
+
+ Compute the sector address of the first
+ sector of IO.SYS.
+
+0000:7D05 8B471A MOV AX,[BX+1A] get starting cluster num
+0000:7D08 48 DEC AX subtract 1
+0000:7D09 48 DEC AX subtract 1
+0000:7D0A 8A1E0D7C MOV BL,[7C0D] sectors per cluster
+0000:7D0E 32FF XOR BH,BH
+0000:7D10 F7E3 MUL BX multiply
+0000:7D12 0306497C ADD AX,[7C49] add start addr of
+0000:7D16 13164B7C ADC DX,[7C4B] root dir (as LBA)
+
+ Read IO.SYS into memory at 0000:0700. IO.SYS
+ is 3 sectors long.
+
+0000:7D1A BB0007 MOV BX,0700 address to read into
+0000:7D1D B90300 MOV CX,0003 read 3 sectors
+
+ READ_LOOP:
+
+ Read the first 3 sectors of IO.SYS
+ (IO.SYS is much longer than 3 sectors).
+
+0000:7D20 50 PUSH AX save AX
+0000:7D21 52 PUSH DX save DX
+0000:7D22 51 PUSH CX save CX
+0000:7D23 E83A00 CALL CONVERT call conversion routine
+0000:7D26 72D8 JB SETUP_TALK jmp if error
+0000:7D28 B001 MOV AL,01 read one sector
+0000:7D2A E85400 CALL READ_SECTORS read one sector
+0000:7D2D 59 POP CX restore CX
+0000:7D2E 5A POP DX restore DX
+0000:7D2F 58 POP AX restore AX
+0000:7D30 72BB JB TALK jmp if any INT 13 error
+0000:7D32 050100 ADD AX,0001 add one to the sector addr
+0000:7D35 83D200 ADC DX,+00 add one to the sector addr
+0000:7D38 031E0B7C ADD BX,[7C0B] incr mem addr by sect size
+0000:7D3C E2E2 LOOP READ_LOOP read next sector
+
+ Leave information in the AX, BX, CX and DX
+ registers for IO.SYS to use. Finally,
+ jump to IO.SYS at 0070:0000.
+
+0000:7D3E 8A2E157C MOV CH,[7C15] media type
+0000:7D42 8A16247C MOV DL,[7C24] drive number
+0000:7D46 8B1E497C MOV BX,[7C49] get start addr of
+0000:7D4A A14B7C MOV AX,[7C4B] root dir (as LBA)
+0000:7D4D EA00007000 JMP 0070:0000 JUMP TO 0070:0000
+
+ MSG_LOOP:
+
+ This routine displays a message using
+ INT 10 one character at a time.
+ The message address is in DS:SI.
+
+0000:7D52 AC LODSB get message character
+0000:7D53 0AC0 OR AL,AL end of message?
+0000:7D55 7429 JZ RETURN jmp if yes
+0000:7D57 B40E MOV AH,0E display one character
+0000:7D59 BB0700 MOV BX,0007 video attrbiutes
+0000:7D5C CD10 INT 10 display one character
+0000:7D5E EBF2 JMP MSG_LOOP do again
+
+ CONVERT:
+ This routine
+ converts a sector address (an LBA) to
+ a CHS address. The LBA is in DX:AX.
+
+0000:7D60 3B16187C CMP DX,[7C18] hi part of LBA > sectPerTrk?
+0000:7D64 7319 JNB SET_CARRY jmp if yes
+0000:7D66 F736187C DIV WORD PTR [7C18] div by sectors per track
+0000:7D6A FEC2 INC DL add 1 to sector number
+0000:7D6C 88164F7C MOV [7C4F],DL save sector number
+0000:7D70 33D2 XOR DX,DX zero DX
+0000:7D72 F7361A7C DIV WORD PTR [7C1A] div number of heads
+0000:7D76 8816257C MOV [7C25],DL save head number
+0000:7D7A A34D7C MOV [7C4D],AX save cylinder number
+0000:7D7D F8 CLC clear carry
+0000:7D7E C3 RET return
+
+ SET_CARRY:
+
+0000:7D7F F9 STC set carry
+
+ RETURN:
+
+0000:7D80 C3 RET return
+
+ READ_SECTORS:
+
+ The caller of this routine supplies:
+ AL = number of sectors to read
+ ES:BX = memory location to read into
+ and CHS address to read from in
+ memory locations 7c25 and 7C4d-7c4f.
+
+0000:7D81 B402 MOV AH,02 INT 13 read sectors
+0000:7D83 8B164D7C MOV DX,[7C4D] get cylinder number
+0000:7D87 B106 MOV CL,06 shift count
+0000:7D89 D2E6 SHL DH,CL shift upper cyl left 6 bits
+0000:7D8B 0A364F7C OR DH,[7C4F] or in sector number
+0000:7D8F 8BCA MOV CX,DX move to CX
+0000:7D91 86E9 XCHG CH,CL CH=cyl lo, CL=cyl hi + sect
+0000:7D93 8A16247C MOV DL,[7C24] drive number
+0000:7D97 8A36257C MOV DH,[7C25] head number
+0000:7D9B CD13 INT 13 read sectors
+0000:7D9D C3 RET return
+
+Data not used.
+
+0000:7D90 ca86e98a 16247c8a 36257ccd 13c3.... *.....$|.6%|... *
+
+Messages here.
+
+0000:7D90 ........ ........ ........ ....0d0a * ..*
+0000:7Da0 4e6f6e2d 53797374 656d2064 69736b20 *Non-System disk *
+0000:7Db0 6f722064 69736b20 6572726f 720d0a52 *or disk error..R*
+0000:7Dc0 65706c61 63652061 6e642070 72657373 *eplace and press*
+0000:7Dd0 20616e79 206b6579 20776865 6e207265 * any key when re*
+0000:7De0 6164790d 0a00.... ........ ........ *ady... *
+
+MS DOS hidden file names (first two root directory entries).
+
+0000:7De0 ........ ....494f 20202020 20205359 * IO SY*
+0000:7Df0 534d5344 4f532020 20535953 000055aa *SMSDOS SYS..U.*
+
+The last two bytes contain a 55AAH signature.
+
+0000:7Df0 ........ ........ ........ ....55aa * U.*
+
+/end/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//
diff --git a/etc/etc.i386/INSTALL.mbr b/etc/etc.i386/INSTALL.mbr
new file mode 100644
index 00000000000..6dcd856d154
--- /dev/null
+++ b/etc/etc.i386/INSTALL.mbr
@@ -0,0 +1,271 @@
+ How It Works -- Master Boot Record
+
+ Version 1a
+
+ by Hale Landis (landis@sugs.tware.com)
+
+
+THE "HOW IT WORKS" SERIES
+
+This is one of several How It Works documents. The series
+currently includes the following:
+
+* How It Works -- CHS Translation
+* How It Works -- Master Boot Record
+* How It Works -- DOS Floppy Boot Sector
+* How It Works -- OS2 Boot Sector
+* How It Works -- Partition Tables
+
+
+MASTER BOOT RECORD
+
+This article is a disassembly of a Master Boot Record (MBR). The
+MBR is the sector at cylinder 0, head 0, sector 1 of a hard disk.
+An MBR is created by the FDISK program. The FDISK program of all
+operating systems must create a functionally similar MBR. The MBR
+is first of what could be many partition sectors, each one
+containing a four entry partition table.
+
+At the completion of your system's Power On Self Test (POST), INT
+19 is called. Usually INT 19 tries to read a boot sector from
+the first floppy drive. If a boot sector is found on the floppy
+disk, the that boot sector is read into memory at location
+0000:7C00 and INT 19 jumps to memory location 0000:7C00.
+However, if no boot sector is found on the first floppy drive,
+INT 19 tries to read the MBR from the first hard drive. If an
+MBR is found it is read into memory at location 0000:7c00 and INT
+19 jumps to memory location 0000:7c00. The small program in the
+MBR will attempt to locate an active (bootable) partition in its
+partition table. If such a partition is found, the boot sector
+of that partition is read into memory at location 0000:7C00 and
+the MBR program jumps to memory location 0000:7C00. Each
+operating system has its own boot sector format. The small
+program in the boot sector must locate the first part of the
+operating system's kernel loader program (or perhaps the kernel
+itself or perhaps a "boot manager program") and read that into
+memory.
+
+INT 19 is also called when the CTRL-ALT-DEL keys are used. On
+most systems, CTRL-ALT-DEL causes an short version of the POST to
+be executed before INT 19 is called.
+
+=====
+
+Where stuff is:
+
+ The MBR program code starts at offset 0000.
+ The MBR messages start at offset 008b.
+ The partition table starts at offset 00be.
+ The signature is at offset 00fe.
+
+Here is a summary of what this thing does:
+
+ If an active partition is found, that partition's boot record
+ is read into 0000:7c00 and the MBR code jumps to 0000:7c00
+ with SI pointing to the partition table entry that describes
+ the partition being booted. The boot record program uses this
+ data to determine the drive being booted from and the location
+ of the partition on the disk.
+
+ If no active partition table enty is found, ROM BASIC is
+ entered via INT 18. All other errors cause a system hang, see
+ label HANG.
+
+NOTES (VERY IMPORTANT):
+
+ 1) The first byte of an active partition table entry is 80.
+ This byte is loaded into the DL register before INT 13 is
+ called to read the boot sector. When INT 13 is called, DL is
+ the BIOS device number. Because of this, the boot sector read
+ by this MBR program can only be read from BIOS device number
+ 80 (the first hard disk). This is one of the reasons why it
+ is usually not possible to boot from any other hard disk.
+
+ 2) The MBR program uses the CHS based INT 13H AH=02H call to
+ read the boot sector of the active partition. The location of
+ the active partition's boot sector is in the partition table
+ entry in CHS format. If the drive is >528MB, this CHS must be
+ a translated CHS (or L-CHS, see my BIOS TYPES document).
+ No addresses in LBA form are used (another reason why LBA
+ doesn't solve the >528MB problem).
+
+=====
+
+Here is the entire MBR record (hex dump and ascii).
+
+OFFSET 0 1 2 3 4 5 6 7 8 9 A B C D E F *0123456789ABCDEF*
+000000 fa33c08e d0bc007c 8bf45007 501ffbfc *.3.....|..P.P...*
+000010 bf0006b9 0001f2a5 ea1d0600 00bebe07 *................*
+000020 b304803c 80740e80 3c00751c 83c610fe *...<.t..<.u.....*
+000030 cb75efcd 188b148b 4c028bee 83c610fe *.u......L.......*
+000040 cb741a80 3c0074f4 be8b06ac 3c00740b *.t..<.t.....<.t.*
+000050 56bb0700 b40ecd10 5eebf0eb febf0500 *V.......^.......*
+000060 bb007cb8 010257cd 135f730c 33c0cd13 *..|...W.._s.3...*
+000070 4f75edbe a306ebd3 bec206bf fe7d813d *Ou...........}.=*
+000080 55aa75c7 8bf5ea00 7c000049 6e76616c *U.u.....|..Inval*
+000090 69642070 61727469 74696f6e 20746162 *id partition tab*
+0000a0 6c650045 72726f72 206c6f61 64696e67 *le.Error loading*
+0000b0 206f7065 72617469 6e672073 79737465 * operating syste*
+0000c0 6d004d69 7373696e 67206f70 65726174 *m.Missing operat*
+0000d0 696e6720 73797374 656d0000 00000000 *ing system......*
+0000e0 00000000 00000000 00000000 00000000 *................*
+0000f0 TO 0001af SAME AS ABOVE
+0001b0 00000000 00000000 00000000 00008001 *................*
+0001c0 0100060d fef83e00 00000678 0d000000 *......>....x....*
+0001d0 00000000 00000000 00000000 00000000 *................*
+0001e0 00000000 00000000 00000000 00000000 *................*
+0001f0 00000000 00000000 00000000 000055aa *..............U.*
+
+=====
+
+Here is the disassembly of the MBR...
+
+This sector is initially loaded into memory at 0000:7c00 but
+it immediately relocates itself to 0000:0600.
+
+ BEGIN: NOW AT 0000:7C00, RELOCATE
+
+0000:7C00 FA CLI disable int's
+0000:7C01 33C0 XOR AX,AX set stack seg to 0000
+0000:7C03 8ED0 MOV SS,AX
+0000:7C05 BC007C MOV SP,7C00 set stack ptr to 7c00
+0000:7C08 8BF4 MOV SI,SP SI now 7c00
+0000:7C0A 50 PUSH AX
+0000:7C0B 07 POP ES ES now 0000:7c00
+0000:7C0C 50 PUSH AX
+0000:7C0D 1F POP DS DS now 0000:7c00
+0000:7C0E FB STI allow int's
+0000:7C0F FC CLD clear direction
+0000:7C10 BF0006 MOV DI,0600 DI now 0600
+0000:7C13 B90001 MOV CX,0100 move 256 words (512 bytes)
+0000:7C16 F2 REPNZ move MBR from 0000:7c00
+0000:7C17 A5 MOVSW to 0000:0600
+0000:7C18 EA1D060000 JMP 0000:061D jmp to NEW_LOCATION
+
+ NEW_LOCATION: NOW AT 0000:0600
+
+0000:061D BEBE07 MOV SI,07BE point to first table entry
+0000:0620 B304 MOV BL,04 there are 4 table entries
+
+ SEARCH_LOOP1: SEARCH FOR AN ACTIVE ENTRY
+
+0000:0622 803C80 CMP BYTE PTR [SI],80 is this the active entry?
+0000:0625 740E JZ FOUND_ACTIVE yes
+0000:0627 803C00 CMP BYTE PTR [SI],00 is this an inactive entry?
+0000:062A 751C JNZ NOT_ACTIVE no
+0000:062C 83C610 ADD SI,+10 incr table ptr by 16
+0000:062F FECB DEC BL decr count
+0000:0631 75EF JNZ SEARCH_LOOP1 jmp if not end of table
+0000:0633 CD18 INT 18 GO TO ROM BASIC
+
+ FOUND_ACTIVE: FOUND THE ACTIVE ENTRY
+
+0000:0635 8B14 MOV DX,[SI] set DH/DL for INT 13 call
+0000:0637 8B4C02 MOV CX,[SI+02] set CH/CL for INT 13 call
+0000:063A 8BEE MOV BP,SI save table ptr
+
+ SEARCH_LOOP2: MAKE SURE ONLY ONE ACTIVE ENTRY
+
+0000:063C 83C610 ADD SI,+10 incr table ptr by 16
+0000:063F FECB DEC BL decr count
+0000:0641 741A JZ READ_BOOT jmp if end of table
+0000:0643 803C00 CMP BYTE PTR [SI],00 is this an inactive entry?
+0000:0646 74F4 JZ SEARCH_LOOP2 yes
+
+ NOT_ACTIVE: MORE THAN ONE ACTIVE ENTRY FOUND
+
+0000:0648 BE8B06 MOV SI,068B display "Invld prttn tbl"
+
+ DISPLAY_MSG: DISPLAY MESSAGE LOOP
+
+0000:064B AC LODSB get char of message
+0000:064C 3C00 CMP AL,00 end of message
+0000:064E 740B JZ HANG yes
+0000:0650 56 PUSH SI save SI
+0000:0651 BB0700 MOV BX,0007 screen attributes
+0000:0654 B40E MOV AH,0E output 1 char of message
+0000:0656 CD10 INT 10 to the display
+0000:0658 5E POP SI restore SI
+0000:0659 EBF0 JMP DISPLAY_MSG do it again
+
+ HANG: HANG THE SYSTEM LOOP
+
+0000:065B EBFE JMP HANG sit and stay!
+
+ READ_BOOT: READ ACTIVE PARITION BOOT RECORD
+
+0000:065D BF0500 MOV DI,0005 INT 13 retry count
+
+ INT13RTRY: INT 13 RETRY LOOP
+
+0000:0660 BB007C MOV BX,7C00
+0000:0663 B80102 MOV AX,0201 read 1 sector
+0000:0666 57 PUSH DI save DI
+0000:0667 CD13 INT 13 read sector into 0000:7c00
+0000:0669 5F POP DI restore DI
+0000:066A 730C JNB INT13OK jmp if no INT 13
+0000:066C 33C0 XOR AX,AX call INT 13 and
+0000:066E CD13 INT 13 do disk reset
+0000:0670 4F DEC DI decr DI
+0000:0671 75ED JNZ INT13RTRY if not zero, try again
+0000:0673 BEA306 MOV SI,06A3 display "Errr ldng systm"
+0000:0676 EBD3 JMP DISPLAY_MSG jmp to display loop
+
+ INT13OK: INT 13 ERROR
+
+0000:0678 BEC206 MOV SI,06C2 "missing op sys"
+0000:067B BFFE7D MOV DI,7DFE point to signature
+0000:067E 813D55AA CMP WORD PTR [DI],AA55 is signature correct?
+0000:0682 75C7 JNZ DISPLAY_MSG no
+0000:0684 8BF5 MOV SI,BP set SI
+0000:0686 EA007C0000 JMP 0000:7C00 JUMP TO THE BOOT SECTOR
+ WITH SI POINTING TO
+ PART TABLE ENTRY
+
+Messages here.
+
+0000:0680 ........ ........ ......49 6e76616c * Inval*
+0000:0690 69642070 61727469 74696f6e 20746162 *id partition tab*
+0000:06a0 6c650045 72726f72 206c6f61 64696e67 *le.Error loading*
+0000:06b0 206f7065 72617469 6e672073 79737465 * operating syste*
+0000:06c0 6d004d69 7373696e 67206f70 65726174 *m.Missing operat*
+0000:06d0 696e6720 73797374 656d00.. ........ *ing system. *
+
+Data not used.
+
+0000:06d0 ........ ........ ......00 00000000 * .....*
+0000:06e0 00000000 00000000 00000000 00000000 *................*
+0000:06f0 00000000 00000000 00000000 00000000 *................*
+0000:0700 00000000 00000000 00000000 00000000 *................*
+0000:0710 00000000 00000000 00000000 00000000 *................*
+0000:0720 00000000 00000000 00000000 00000000 *................*
+0000:0730 00000000 00000000 00000000 00000000 *................*
+0000:0740 00000000 00000000 00000000 00000000 *................*
+0000:0750 00000000 00000000 00000000 00000000 *................*
+0000:0760 00000000 00000000 00000000 00000000 *................*
+0000:0770 00000000 00000000 00000000 00000000 *................*
+0000:0780 00000000 00000000 00000000 00000000 *................*
+0000:0790 00000000 00000000 00000000 00000000 *................*
+0000:07a0 00000000 00000000 00000000 00000000 *................*
+0000:07b0 00000000 00000000 00000000 0000.... *............ *
+
+The partition table starts at 0000:07be. Each partition table
+entry is 16 bytes. This table defines a single primary partition
+which is also an active (bootable) partition.
+
+0000:07b0 ........ ........ ........ ....8001 * ....*
+0000:07c0 0100060d fef83e00 00000678 0d000000 *......>....x....*
+0000:07d0 00000000 00000000 00000000 00000000 *................*
+0000:07e0 00000000 00000000 00000000 00000000 *................*
+0000:07f0 00000000 00000000 00000000 0000.... *............ *
+
+The last two bytes contain a 55AAH signature.
+
+0000:07f0 ........ ........ ........ ....55aa *..............U.*
+
+/end/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//
diff --git a/etc/etc.i386/INSTALL.os2br b/etc/etc.i386/INSTALL.os2br
new file mode 100644
index 00000000000..6f243869484
--- /dev/null
+++ b/etc/etc.i386/INSTALL.os2br
@@ -0,0 +1,469 @@
+ How It Works -- OS2 Boot Sector
+
+ Version 1a
+
+ by Hale Landis (landis@sugs.tware.com)
+
+
+THE "HOW IT WORKS" SERIES
+
+This is one of several How It Works documents. The series
+currently includes the following:
+
+* How It Works -- CHS Translation
+* How It Works -- Master Boot Record
+* How It Works -- DOS Floppy Boot Sector
+* How It Works -- OS2 Boot Sector
+* How It Works -- Partition Tables
+
+
+OS2 BOOT SECTOR
+
+Note: I'll leave it to someone else to provide you with a
+disassembly of an OS/2 HPFS boot sector, or a Linux boot sector,
+or a WinNT boot sector, etc.
+
+This article is a disassembly of a floppy or hard disk boot
+sector for OS/2. Apparently OS/2 uses the same boot sector for
+both environments. Basically a bootable FAT hard disk partition
+looks like a big floppy during the early stages of the system's
+boot processing. This sector is at cylinder 0, head 0, sector 1
+of a floppy or it is the first sector within a FAT hard disk
+partition. OS/2 floppy disk and hard disk boot sectors are
+created by the OS/2 FORMAT program.
+
+At the completion of your system's Power On Self Test (POST), INT
+19 is called. Usually INT 19 tries to read a boot sector from
+the first floppy drive. If a boot sector is found on the floppy
+disk, the that boot sector is read into memory at location
+0000:7C00 and INT 19 jumps to memory location 0000:7C00.
+However, if no boot sector is found on the first floppy drive,
+INT 19 tries to read the MBR from the first hard drive. If an
+MBR is found it is read into memory at location 0000:7c00 and INT
+19 jumps to memory location 0000:7c00. The small program in the
+MBR will attempt to locate an active (bootable) partition in its
+partition table. If such a partition is found, the boot sector
+of that partition is read into memory at location 0000:7C00 and
+the MBR program jumps to memory location 0000:7C00. Each
+operating system has its own boot sector format. The small
+program in the boot sector must locate the first part of the
+operating system's kernel loader program (or perhaps the kernel
+itself or perhaps a "boot manager program") and read that into
+memory.
+
+INT 19 is also called when the CTRL-ALT-DEL keys are used. On
+most systems, CTRL-ALT-DEL causes an short version of the POST to
+be executed before INT 19 is called.
+
+=====
+
+Where stuff is:
+
+ The BIOS Parameter Block (BPB) starts at offset 0.
+ The boot sector program starts at offset 46.
+ The messages issued by this program start at offset 198.
+ The OS/2 boot loader file name starts at offset 1d5.
+ The boot sector signature is at offset 1fe.
+
+Here is a summary of what this thing does:
+
+ 1) If booting from a hard disk partition, skip to step 6.
+ 2) Copy Diskette Parameter Table which is pointed to by INT 1E
+ to the top of memory.
+ 3) Alter the copy of the Diskette Parameter Table.
+ 4) Alter INT 1E to point to altered Diskette Parameter Table at
+ the top of memory.
+ 5) Do INT 13 AH=00, disk reset call so that the altered
+ Diskette Parameter Table is used.
+ 6) Compute sector address of the root directory.
+ 7) Read the entire root directory into memory starting at
+ location 1000:0000.
+ 8) Search the root directory entires for the file OS2BOOT.
+ 9) Read the OS2BOOT file into memory at 0800:0000.
+10) Do a far return to enter the OS2BOOT program at 0800:0000.
+
+NOTES:
+
+ This program uses the CHS based INT 13H AH=02 to read the FAT
+ root directory and to read the OS2BOOT file. If the drive is
+ >528MB, this CHS must be a translated CHS (or L-CHS, see my
+ BIOS TYPES document). Except for internal computations no
+ addresses in LBA form are used, another reason why LBA doesn't
+ solve the >528MB problem.
+
+=====
+
+Here is the entire sector in hex and ascii.
+
+OFFSET 0 1 2 3 4 5 6 7 8 9 A B C D E F *0123456789ABCDEF*
+000000 eb449049 424d2032 302e3000 02100100 *.D.IBM 20.0.....*
+000010 02000200 00f8d800 3e000e00 3e000000 *........>...>...*
+000020 06780d00 80002900 1c0c234e 4f204e41 *.x....)...#NO NA*
+000030 4d452020 20204641 54202020 20200000 *ME FAT ..*
+000040 00100000 0000fa33 db8ed3bc ff7bfbba *.......3.....{..*
+000050 c0078eda 803e2400 00753d1e b840008e *.....>$..u=..@..*
+000060 c026ff0e 1300cd12 c1e0068e c033ff33 *.&...........3.3*
+000070 c08ed8c5 367800fc b90b00f3 a41fa118 *....6x..........*
+000080 0026a204 001e33c0 8ed8a378 008c067a *.&....3....x...z*
+000090 001f8a16 2400cd13 a0100098 f7261600 *....$........&..*
+0000a0 03060e00 5091b820 00f72611 008b1e0b *....P.. ..&.....*
+0000b0 0003c348 f7f35003 c1a33e00 b800108e *...H..P...>.....*
+0000c0 c033ff59 890e4400 58a34200 33d2e873 *.3.Y..D.X.B.3..s*
+0000d0 0033db8b 0e11008b fb51b90b 00bed501 *.3.......Q......*
+0000e0 f3a65974 0583c320 e2ede335 268b471c *..Yt... ...5&.G.*
+0000f0 268b571e f7360b00 fec08ac8 268b571a *&.W..6......&.W.*
+000100 4a4aa00d 0032e4f7 e203063e 0083d200 *JJ...2.....>....*
+000110 bb00088e c333ff06 57e82800 8d360b00 *.....3..W.(..6..*
+000120 cbbe9801 eb03bead 01e80900 bec201e8 *................*
+000130 0300fbeb feac0ac0 7409b40e bb0700cd *........t.......*
+000140 10ebf2c3 50525103 061c0013 161e00f7 *....PRQ.........*
+000150 361800fe c28ada33 d2f7361a 008afa8b *6......3..6.....*
+000160 d0a11800 2ac34050 b402b106 d2e60af3 *....*.@P........*
+000170 8bca86e9 8a162400 8af78bdf cd1372a6 *......$.......r.*
+000180 5b598bc3 f7260b00 03f85a58 03c383d2 *[Y...&....ZX....*
+000190 002acb7f afc31200 4f532f32 20212120 *.*......OS/2 !! *
+0001a0 53595330 31343735 0d0a0012 004f532f *SYS01475.....OS/*
+0001b0 32202121 20535953 30323032 350d0a00 *2 !! SYS02025...*
+0001c0 12004f53 2f322021 21205359 53303230 *..OS/2 !! SYS020*
+0001d0 32370d0a 004f5332 424f4f54 20202020 *27...OS2BOOT *
+0001e0 00000000 00000000 00000000 00000000 *................*
+0001f0 00000000 00000000 00000000 000055aa *..............U.*
+
+=====
+
+The first 62 bytes of a boot sector are known as the BIOS
+Parameter Block (BPB). Here is the layout of the BPB fields
+and the values they are assigned in this boot sector:
+
+ db JMP instruction at 7c00 size 2 = eb44
+ db NOP instruction 7c02 1 90
+ db OEMname 7c03 8 'IBM 20.0'
+ dw bytesPerSector 7c0b 2 0200
+ db sectPerCluster 7c0d 1 01
+ dw reservedSectors 7c0e 2 0001
+ db numFAT 7c10 1 02
+ dw numRootDirEntries 7c11 2 0200
+ dw numSectors 7c13 2 0000 (use numSectorsHuge)
+ db mediaType 7c15 1 f8
+ dw numFATsectors 7c16 2 00d8
+ dw sectorsPerTrack 7c18 2 003e
+ dw numHeads 7c1a 2 000e
+ dd numHiddenSectors 7c1c 4 00000000
+ dd numSectorsHuge 7c20 4 000d7806
+ db driveNum 7c24 1 80
+ db reserved 7c25 1 00
+ db signature 7c26 1 29
+ dd volumeID 7c27 4 001c0c23
+ db volumeLabel 7c2b 11 'NO NAME '
+ db fileSysType 7c36 8 'FAT '
+
+=====
+
+Here is the boot sector...
+
+The first 3 bytes of the BPB are JMP and NOP instructions.
+
+0000:7C00 EB44 JMP START
+0000:7C02 90 NOP
+
+Here is the rest of the BPB.
+
+0000:7C00 eb449049 424d2032 302e3000 02100100 *.D.IBM 20.0.....*
+0000:7C10 02000200 00f8d800 3e000e00 3e000000 *........>...>...*
+0000:7C20 06780d00 80002900 1c0c234e 4f204e41 *.x....)...#NO NA*
+0000:7C30 4d452020 20204641 54202020 20200000 *ME FAT ..*
+
+Additional data areas.
+
+0000:7C30 ........ ........ ........ ....0000 * ..*
+0000:7C40 00100000 0000.... ........ ........ *...... *
+
+ Note:
+
+ 0000:7c3e (DS:003e) = number of sectors in the FATs and root dir.
+ 0000:7c42 (DS:0042) = number of sectors in the FAT.
+ 0000:7c44 (DS:0044) = number of sectors in the root dir.
+
+ START: START OF BOOT SECTOR PROGRAM
+
+0000:7C46 FA CLI interrupts off
+0000:7C47 33DB XOR BX,BX zero BX
+0000:7C49 8ED3 MOV SS,BX SS now zero
+0000:7C4B BCFF7B MOV SP,7BFF SP now 7bff
+0000:7C4E FB STI interrupts on
+0000:7C4F BAC007 MOV DX,07C0 set DX to
+0000:7C52 8EDA MOV DS,DX 07c0
+
+ Are we booting from a floppy or a
+ hard disk partition?
+
+0000:7C54 803E240000 CMP BYTE PTR [0024],00 is driveNum in BPB 00?
+0000:7C59 753D JNZ NOT_FLOPPY jmp if not zero
+
+ We are booting from a floppy. The
+ Diskette Parameter Table must be
+ copied and altered...
+
+ Diskette Parameter Table is pointed to by INT 1E. This
+ program moves this table to high memory, alters the table, and
+ changes INT 1E to point to the altered table.
+
+ This table contains the following data:
+
+ ????:0000 = Step rate and head unload time.
+ ????:0001 = Head load time and DMA mode flag.
+ ????:0002 = Delay for motor turn off.
+ ????:0003 = Bytes per sector.
+ ????:0004 = Sectors per track.
+ ????:0005 = Intersector gap length.
+ ????:0006 = Data length.
+ ????:0007 = Intersector gap length during format.
+ ????:0008 = Format byte value.
+ ????:0009 = Head settling time.
+ ????:000a = Delay until motor at normal speed.
+
+ Compute a valid high memory address.
+
+0000:7C5B 1E PUSH DS save DS
+0000:7C5C B84000 MOV AX,0040 set ES
+0000:7C5F 8EC0 MOV ES,AX to 0040 (BIOS data area)
+0000:7C61 26 ES: reduce system memory
+0000:7C62 FF0E1300 DEC WORD PTR [0013] size by 1024
+0000:7C66 CD12 INT 12 get system memory size
+0000:7C68 C1E06 SHL AX,06 shift AX (mult by 64)
+0000:7C6B 8EC0 MOV ES,AX move to ES
+0000:7C6D 33FF XOR DI,DI zero DI
+
+ Move the diskette param table to high memory.
+
+0000:7C6F 33C0 XOR AX,AX zero AX
+0000:7C71 8ED8 MOV DS,AX DS now zero
+0000:7C73 C5367800 LDS SI,[0078] DS:SI = INT 1E vector
+0000:7C77 FC CLD clear direction
+0000:7C78 B90B00 MOV CX,000B count is 11
+0000:7C7B F3 REPZ copy diskette param table
+0000:7C7C A4 MOVSB to top of memory
+
+ Alter the number of sectors per track
+ in the diskette param table in high memory.
+
+0000:7C7D 1F POP DS restore DS
+0000:7C7E A11800 MOV AX,[0018] get sectorsPerTrack from BPB
+0000:7C81 26 ES: alter sectors per track
+0000:7C82 A20400 MOV [0004],AL in diskette param table
+
+ Change INT 1E to point to altered diskette
+ param table and do a INT 13 disk reset call.
+
+0000:7C85 1E PUSH DS save DS
+0000:7C86 33C0 XOR AX,AX AX now zero
+0000:7C88 8ED8 MOV DS,AX DS no zero
+0000:7C8A A37800 MOV [0078],AX alter INT 1E vector
+0000:7C8D 8C067A00 MOV [007A],ES to point to altered
+ diskette param table
+0000:7C91 1F POP DS restore DS
+0000:7C92 8A162400 MOV DL,[0024] driveNum from BPB
+0000:7C96 CD13 INT 13 diskette reset
+
+ NOT_FLOPPY:
+
+ Compute the location and the size of
+ the root directory. Read the entire
+ root directory into memory.
+
+0000:7C98 A01000 MOV AL,[0010] get numFAT
+0000:7C9B 98 CBW make into a word
+0000:7C9C F7261600 MUL WORD PTR [0016] mult by numFatSectors
+0000:7CA0 03060E00 ADD AX,[000E] add reservedSectors
+0000:7CA4 50 PUSH AX save
+0000:7CA5 91 XCHG CX,AX move to CX
+0000:7CA6 B82000 MOV AX,0020 dir entry size
+0000:7CA9 F7261100 MUL WORD PTR [0011] mult by numRootDirEntries
+0000:7CAD 8B1E0B00 MOV BX,[000B] get bytesPerSector
+0000:7CB1 03C3 ADD AX,BX add
+0000:7CB3 48 DEC AX subtract 1
+0000:7CB4 F7F3 DIV BX div by bytesPerSector
+0000:7CB6 50 PUSH AX save number of dir sectors
+0000:7CB7 03C1 ADD AX,CX add number of fat sectors
+0000:7CB9 A33E00 MOV [003E],AX save
+0000:7CBC B80010 MOV AX,1000 AX is now 1000
+0000:7CBF 8EC0 MOV ES,AX ES is now 1000
+0000:7CC1 33FF XOR DI,DI DI is now zero
+0000:7CC3 59 POP CX get number dir sectors
+0000:7CC4 890E4400 MOV [0044],CX save
+0000:7CC8 58 POP AX get number fat sectors
+0000:7CC9 A34200 MOV [0042],AX save
+0000:7CCC 33D2 XOR DX,DX DX now zero
+0000:7CCE E87300 CALL READ_SECTOR read 1st sect of root dir
+0000:7CD1 33DB XOR BX,BX BX is now zero
+0000:7CD3 8B0E1100 MOV CX,[0011] number of root dir entries
+
+ DIR_SEARCH: SEARCH FOR OS2BOOT.
+
+ Search the root directory for the file
+ name OS2BOOT.
+
+0000:7CD7 8BFB MOV DI,BX DI is dir entry addr
+0000:7CD9 51 PUSH CX save CX
+0000:7CDA B90B00 MOV CX,000B count is 11
+0000:7CDD BED501 MOV SI,01D5 addr of "OS2BOOT"
+0000:7CE0 F3 REPZ is 1st dir entry
+0000:7CE1 A6 CMPSB for "OS2BOOT"?
+0000:7CE2 59 POP CX restore CX
+0000:7CE3 7405 JZ FOUND_OS2BOOT jmp if OS2BOOT
+0000:7CE5 83C320 ADD BX,+20 incr to next dir entry
+0000:7CE8 E2ED LOOP DIR_SEARCH try again
+
+ FOUND_OS2BOOT: FOUND OS2BOOT.
+
+ OS2BOOT was found. Get the starting
+ cluster number and convert to a sector
+ address. Read OS2BOOT into memory and
+ finally do a far return to enter
+ the OS2BOOT program.
+
+0000:7CEA E335 JCXZ FAILED1 JMP if CX zero.
+0000:7CEC 26 ES: get the szie of
+0000:7CED 8B471C MOV AX,[BX+1C] the OS2BOOT file
+0000:7CF0 26 ES: from the OS2BOOT
+0000:7CF1 8B571E MOV DX,[BX+1E] directory entry
+0000:7CF4 F7360B00 DIV WORD PTR [000B] div by bytesPerSect
+0000:7CF8 FEC0 INC AL add 1
+0000:7CFA 8AC8 MOV CL,AL num sectors OS2BOOT
+0000:7CFC 26 ES: get the starting
+0000:7CFD 8B571A MOV DX,[BX+1A] cluster number
+0000:7D00 4A DEC DX subtract 1
+0000:7D01 4A DEC DX subtract 1
+0000:7D02 A00D00 MOV AL,[000D] sectorsPerCluster
+0000:7D05 32E4 XOR AH,AH mutiply
+0000:7D07 F7E2 MUL DX to get LBA
+0000:7D09 03063E00 ADD AX,[003E] add number of FAT sectors
+0000:7D0D 83D200 ADC DX,+00 to LBA
+0000:7D10 BB0008 MOV BX,0800 set ES
+0000:7D13 8EC3 MOV ES,BX to 0800
+0000:7D15 33FF XOR DI,DI set ES:DI to entry point
+0000:7D17 06 PUSH ES address of
+0000:7D18 57 PUSH DI OS2BOOT
+0000:7D19 E82800 CALL READ_SECTOR read OS2BOOT into memory
+0000:7D1C 8D360B00 LEA SI,[000B] set DS:SI
+0000:7D20 CB RETF "far return" to OS2BOOT
+
+ FAILED1: OS2BOOT WAS NOT FOUND.
+
+0000:7D21 BE9801 MOV SI,0198 "SYS01475" message
+0000:7D24 EB03 JMP FAILED3
+
+ FAILED2: ERROR FROM INT 13.
+
+0000:7D26 BEAD01 MOV SI,01AD "SYS02025" message
+
+ FAILED3: OUTPUT ERROR MESSAGES.
+
+0000:7D29 E80900 CALL MSG_LOOP display message
+0000:7D2C BEC201 MOV SI,01C2 "SYS02027" message
+0000:7D2F E80300 CALL MSG_LOOP display message
+0000:7D32 FB STI interrupts on
+
+ HANG: HANG THE SYSTEM!
+
+0000:7D33 EBFE JMP HANG sit and stay!
+
+ MSG_LOOP: DISPLAY AN ERROR MESSAGE.
+
+ Routine to display the message
+ text pointed to by SI.
+
+0000:7D35 AC LODSB get next char of message
+0000:7D36 0AC0 OR AL,AL end of message?
+0000:7D38 7409 JZ RETURN jmp if yes
+0000:7D3A B40E MOV AH,0E write 1 char
+0000:7D3C BB0700 MOV BX,0007 video attributes
+0000:7D3F CD10 INT 10 INT 10 to write 1 char
+0000:7D41 EBF2 JMP MSG_LOOP do again
+
+ RETURN:
+
+0000:7D43 C3 RET return
+
+ READ_SECTOR: ROUTINE TO READ SECTORS.
+
+ Read sectors into memory. Read multiple
+ sectors but don't read across a track
+ boundary.
+
+ The caller supplies the following:
+ DX:AX = sector address to read (as LBA)
+ CX = number of sectors to read
+ ES:DI = memory address to read into
+
+0000:7D44 50 PUSH AX save lower part of LBA
+0000:7D45 52 PUSH DX save upper part of LBA
+0000:7D46 51 PUSH CX save number of sect to read
+0000:7D47 03061C00 ADD AX,[001C] add numHiddenSectors
+0000:7D4B 13161E00 ADC DX,[001E] to LBA
+0000:7D4F F7361800 DIV WORD PTR [0018] div by sectorsPerTrack
+0000:7D53 FEC2 INC DL add 1 to sector number
+0000:7D55 8ADA MOV BL,DL save sector number
+0000:7D57 33D2 XOR DX,DX zero upper part of LBA
+0000:7D59 F7361A00 DIV WORD PTR [001A] div by numHeads
+0000:7D5D 8AFA MOV BH,DL save head number
+0000:7D5F 8BD0 MOV DX,AX save cylinder number
+0000:7D61 A11800 MOV AX,[0018] sectorsPerTrack
+0000:7D64 2AC3 SUB AL,BL sub sector number
+0000:7D66 40 INC AX add 1
+0000:7D67 50 PUSH AX save number of sector to read
+0000:7D68 B402 MOV AH,02 INT 13 read sectors
+0000:7D6A B106 MOV CL,06 shift count
+0000:7D6C D2E6 SHL DH,CL shift high cyl left
+0000:7D6E 0AF3 OR DH,BL or in sector number
+0000:7D70 8BCA MOV CX,DX move cyl/sect to CX
+0000:7D72 86E9 XCHG CH,CL swap cyl/sect
+0000:7D74 8A162400 MOV DL,[0024] driveNum
+0000:7D78 8AF7 MOV DH,BH head number
+0000:7D7A 8BDF MOV BX,DI memory addr to read into
+0000:7D7C CD13 INT 13 INT 13 read sectors call
+0000:7D7E 72A6 JB FAILED2 jmp if any error
+0000:7D80 5B POP BX get number of sectors read
+0000:7D81 59 POP CX restore CX
+0000:7D82 8BC3 MOV AX,BX number of sector to AX
+0000:7D84 F7260B00 MUL WORD PTR [000B] multiply by sector size
+0000:7D88 03F8 ADD DI,AX add to memory address
+0000:7D8A 5A POP DX restore upper part of LBA
+0000:7D8B 58 POP AX resotre lower part of LBA
+0000:7D8C 03C3 ADD AX,BX add number of sector just
+0000:7D8E 83D200 ADC DX,+00 read to LBA
+0000:7D91 2ACB SUB CL,BL decr requested num of sect
+0000:7D93 7FAF JG READ_SECTOR jmp if not zero
+0000:7D95 C3 RET return
+
+Data not used.
+
+0000:7D90 ........ ....1200 ........ ........ * .. *
+
+Messages here.
+
+0000:7D90 ........ ........ 4f532f32 20212120 * OS/2 !! *
+0000:7Da0 53595330 31343735 0d0a0012 004f532f *SYS01475.....OS/*
+0000:7Db0 32202121 20535953 30323032 350d0a00 *2 !! SYS02025...*
+0000:7Dc0 12004f53 2f322021 21205359 53303230 *..OS/2 !! SYS020*
+0000:7Dd0 32370d0a 00...... ........ ........ *27... *
+
+OS/2 loader file name.
+
+0000:7Dd0 ........ ..4f5332 424f4f54 20202020 * OS2BOOT *
+
+Data not used.
+
+0000:7De0 00000000 00000000 00000000 00000000 *................*
+0000:7Df0 00000000 00000000 00000000 0000.... *.............. *
+
+The last two bytes contain a 55AAH signature.
+
+0000:7Df0 ........ ........ ........ ....55aa * U.*
+
+/end/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//
diff --git a/etc/etc.i386/INSTALL.pt b/etc/etc.i386/INSTALL.pt
new file mode 100644
index 00000000000..9cc21328dfe
--- /dev/null
+++ b/etc/etc.i386/INSTALL.pt
@@ -0,0 +1,340 @@
+ How it Works -- Partition Tables
+
+ Version 1c
+
+ by Hale Landis (landis@sugs.tware.com)
+
+
+THE "HOW IT WORKS" SERIES
+
+This is one of several How It Works documents. The series
+currently includes the following:
+
+* How It Works -- CHS Translation
+* How It Works -- Master Boot Record
+* How It Works -- DOS Floppy Boot Sector
+* How It Works -- OS2 Boot Sector
+* How It Works -- Partition Tables
+
+
+PARTITION SECTOR/RECORD/TABLE BASICS
+
+FDISK creates all partition records (sectors). The primary
+purpose of a partition record is to hold a partition table. The
+rules for how FDISK works are unwritten but so far most FDISK
+programs (DOS, OS/2, WinNT, etc) seem to follow the same basic
+idea.
+
+First, all partition table records (sectors) have the same
+format. This includes the partition table record at cylinder 0,
+head 0, sector 1 -- what is known as the Master Boot Record
+(MBR). The last 66 bytes of a partition table record contain a
+partition table and a 2 byte signature. The first 446 bytes of
+these sectors usually contain a program but only the program in
+the MBR is ever executed (so extended partition table records
+could contain something other than a program in the first 466
+bytes). See "How It Works -- The Master Boot Record".
+
+Second, extended partitions are "nested" inside one another and
+extended partition table records form a "linked list". I will
+attempt to show this in a diagram below.
+
+PARTITION TABLE ENTRY FORMAT
+
+Each partition table entry is 16 bytes and contains things like
+the start and end location of a partition in CHS, the start in
+LBA, the size in sectors, the partition "type" and the "active"
+flag. Warning: older versions of FDISK may compute incorrect
+LBA or size values. And note: When your computer boots itself,
+only the CHS fields of the partition table entries are used
+(another reason LBA doesn't solve the >528MB problem). The CHS
+fields in the partition tables are in L-CHS format -- see "How It
+Works -- CHS Translation".
+
+There is no central clearing house to assign the codes used in
+the one byte "type" field. But codes are assigned (or used) to
+define most every type of file system that anyone has ever
+implemented on the x86 PC: 12-bit FAT, 16-bit FAT, HPFS, NTFS,
+etc. Plus, an extended partition also has a unique type code.
+
+Note: I know of no complete list of all the type codes that have
+been used to date. However, I try to include such a list in a
+future version of this document.
+
+The 16 bytes of a partition table entry are used as follows:
+
+ +--- Bit 7 is the active partition flag, bits 6-0 are zero.
+ |
+ | +--- Starting CHS in INT 13 call format.
+ | |
+ | | +--- Partition type byte.
+ | | |
+ | | | +--- Ending CHS in INT 13 call format.
+ | | | |
+ | | | | +-- Starting LBA.
+ | | | | |
+ | | | | | +-- Size in sectors.
+ | | | | | |
+ v <--+---> v <--+--> v v
+
+ 0 1 2 3 4 5 6 7 8 9 A B C D E F
+ DH DL CH CL TB DL CH CL LBA..... SIZE....
+
+ 80 01 01 00 06 0e be 94 3e000000 0c610900 1st entry
+
+ 00 00 81 95 05 0e fe 7d 4a610900 724e0300 2nd entry
+
+ 00 00 00 00 00 00 00 00 00000000 00000000 3rd entry
+
+ 00 00 00 00 00 00 00 00 00000000 00000000 4th entry
+
+Bytes 0-3 are used by the small program in the Master Boot Record
+to read the first sector of an active partition into memory. The
+DH, DL, CH and CL above show which x86 register is loaded when
+the MBR program calls INT 13H AH=02H to read the active
+partition's boot sector. See "How It Works -- Master Boot
+Record".
+
+These entries define the following partitions:
+
+1) The first partition, a primary partition DOS FAT, starts at
+ CHS 0H,1H,1H (LBA 3EH) and ends at CHS 294H,EH,3EH with a size
+ of 9610CH sectors.
+
+2) The second partition, an extended partition, starts at CHS
+ 295H,0H,1H (LBA 9614AH) and ends at CHS 37DH,EH,3EH with a
+ size of 34E72H sectors.
+
+3) The third and fourth table entries are unused.
+
+PARTITION TABLE RULES
+
+Keep in mind that there are NO written rules and NO industry
+standards on how FDISK should work but here are some basic rules
+that seem to be followed by most versions of FDISK:
+
+1) In the MBR there can be 0-4 "primary" partitions, OR, 0-3
+ primary partitions and 0-1 extended partition entry.
+
+2) In an extended partition there can be 0-1 "secondary"
+ partition entries and 0-1 extended partition entries.
+
+3) Only 1 primary partition in the MBR can be marked "active" at
+ any given time.
+
+4) In most versions of FDISK, the first sector of a partition
+ will be aligned such that it is at head 0, sector 1 of a
+ cylinder. This means that there may be unused sectors on the
+ track(s) prior to the first sector of a partition and that
+ there may be unused sectors following a partition table
+ sector.
+
+ For example, most new versions of FDISK start the first
+ partition (primary or extended) at cylinder 0, head 1, sector
+ 1. This leaves the sectors at cylinder 0, head 0, sectors
+ 2...n as unused sectors. This same layout may be seen on the
+ first track of an extended partition. See example 2 below.
+
+ Also note that software drivers like Ontrack's Disk Manager
+ depend on these unused sectors because these drivers will
+ "hide" their code there (in cylinder 0, head 0, sectors
+ 2...n). This is also a good place for boot sector virus
+ programs to hang out.
+
+5) The partition table entries (slots) can be used in any order.
+ Some versions of FDISK fill the table from the bottom up and
+ some versions of FDISK fill the table from the top down.
+ Deleting a partition can leave an unused entry (slot) in the
+ middle of a table.
+
+6) And then there is the "hack" that some newer OS's (OS/2 and
+ Linux) use in order to place a partition spanning or passed
+ cylinder 1024 on a system that does not have a CHS translating
+ BIOS. These systems create a partition table entry with the
+ partition's starting and ending CHS information set to all
+ FFH. The starting and ending LBA information is used to
+ describe the location of the partition. The LBA can be
+ converted back to a CHS -- most likely a CHS with more than
+ 1024 cylinders. Since such a CHS can't be used by the system
+ BIOS, these partitions can not be booted or accessed until the
+ OS's kernel and hard disk device drivers are loaded. It is
+ not known if the systems using this "hack" follow the same
+ rules for the creation of these type of partitions.
+
+There are NO written rules as to how an OS scans the partition
+table entries so each OS can have a different method. For DOS,
+this means that different versions could assign different drive
+letters to the same FAT file system partitions.
+
+PARTITION NESTING
+
+What do I mean when I say the partitions are "nested" within each
+other? Lets look at this example:
+
+ M = Master Boot Record (and any unused sectors
+ on the same track)
+ E = Extended partition record (and any unused sectors
+ on the same track)
+ pri = a primary partition (first sector is a "boot" sector)
+ sec = a secondary partition (first sector is a "boot" sector)
+
+
+ |<----------------the entire disk-------------->|
+ | |
+ |M<pri> |
+ | |
+ | E<sec><---rest of 1st ext part---------->|
+ | |
+ | E<sec><---rest of 2nd ext part---->|
+
+
+The first extended partition is described in the MBR and it
+occupies the entire disk following the primary partition. The
+second extended partition is described in the first extended
+partition record and it occupies the entire disk following the
+first secondary partition.
+
+PARTITION TABLE LINKING
+
+What do I mean when I say the partition records (tables) form a
+"linked" list? This means that the MBR has an entry that
+describes (points to) the first extended partition, the first
+extended partition table has an entry that describes (points to)
+the second extended partition table, and so on. There is, in
+theory, no limited to out long this linked list is. When you ask
+FDISK to show the DOS "logical drives" it scans the linked list
+looking for all of the DOS FAT type partitions that may exist.
+Remember that in an extended partition table, only two entries of
+the four can be used (rule 2 above).
+
+And one more thing... Within a partition, the layout of the file
+system data varies greatly. However, the first sector of a
+partition is expected to be a "boot" sector. A DOS FAT file
+system has: a boot sector, first FAT sectors, second FAT
+sectors, root directory sectors and finally the file data area.
+See "How It Works -- OS2 Boot Sector".
+
+
+EXAMPLE 1
+
+A disk containing four DOS FAT partitions (C, D, E and F):
+
+
+ |<---------------------the entire disk------------------->|
+ | |
+ |M<---C:---> |
+ | |
+ | E<---D:---><-rest of 1st ext part------------>|
+ | |
+ | E<---E:---><-rest of 2nd ext part->|
+ | |
+ | E<---------F:---------->|
+
+
+EXAMPLE 2
+
+So here is an example of a disk with two primary partitions, one
+DOS FAT and one OS/2 HPFS, plus an extended partition with
+another DOS FAT:
+
+
+ |<------------------the entire disk------------------>|
+ | |
+ |M<pri 1 - DOS FAT> |
+ | |
+ | <pri 2 - OS/2 HPFS> |
+ | |
+ | E<sec - DOS FAT>|
+
+
+Or in more detail ('n' is the highest cylinder, head or sector
+number number allowed in the indicated field of the CHS)...
+
+
+ +-------------------------------------+
+ CHS=0,0,1 | Master Boot Record containing |
+ | partition table search program and |
+ | a partition table |
+ | +---------------------------------+ |
+ | | DOS FAT partition description | | points to CHS=0,1,1
+ | +---------------------------------+ | points to CHS=a
+ | | OS/2 HPFS partition description | |
+ | +---------------------------------+ |
+ | | unused table entry | |
+ | +---------------------------------+ |
+ | | extended partition entry | | points to CHS=b
+ | +---------------------------------+ |
+ +-------------------------------------+
+CHS=0,0,2 | the rest of "track 0" -- this is | :
+to | where the software drivers such as | : normally
+CHS=0,0,n | Ontrack's Disk Manager or Micro | : unused
+ | House's EZ Drive are located. | :
+ +-------------------------------------+
+CHS=0,1,1 | Boot sector for the DOS FAT | :
+ | partition | : a DOS FAT
+ +-------------------------------------+ : file
+CHS=0,1,2 | rest of the DOS FAT partition | : system
+to | (FAT table, root directory and | :
+CHS=x-1,n,n | user data area) | :
+ +-------------------------------------+
+CHS=x,0,1 | Boot sector for the OS/2 HPFS | :
+ | file system partition | : an OS/2
+ +-------------------------------------+ : HPFS file
+CHS=x,0,2 | rest of the OS/2 HPFS file system | : system
+to | partition | :
+CHS=y-1,n,n | | :
+ +-------------------------------------+
+CHS=y,0,1 | Partition record for the extended |
+ | partition containing a partition |
+ | record program (never executed) and |
+ | a partition table |
+ | +---------------------------------+ |
+ | | DOS FAT partition description | | points to CHS=b+1
+ | +---------------------------------+ |
+ | | unused table entry | |
+ | +---------------------------------+ |
+ | | unused table entry | |
+ | +---------------------------------+ |
+ | | unused table entry | |
+ | +---------------------------------+ |
+ +-------------------------------------+
+CHS=y,0,2 | the rest of the first track of the | : normally
+to | extended partition | : unused
+CHS=y,0,n | | :
+ +-------------------------------------+
+CHS=y,1,1 | Boot sector for the DOS FAT | :
+ | partition | : a DOS FAT
+ +-------------------------------------+ : file
+CHS=y,1,2 | rest of the DOS FAT partition | : system
+to | (FAT table, root directory and | :
+CHS=n,n,n | user data area) | :
+ +-------------------------------------+
+
+EXAMPLE 3
+
+Here is a partition record from an extended partition (the first
+sector of an extended partition). Note that it contains no
+program code. It contains only the partition table and the
+signature data.
+
+OFFSET 0 1 2 3 4 5 6 7 8 9 A B C D E F *0123456789ABCDEF*
+000000 00000000 00000000 00000000 00000000 *................*
+000010 TO 0001af SAME AS ABOVE
+0001b0 00000000 00000000 00000000 00000001 *................*
+0001c0 8195060e fe7d3e00 0000344e 03000000 *.....}>...4N....*
+0001d0 00000000 00000000 00000000 00000000 *................*
+0001e0 00000000 00000000 00000000 00000000 *................*
+0001f0 00000000 00000000 00000000 000055aa *..............U.*
+
+NOTES
+
+Thanks to yue@heron.Stanford.EDU (Kenneth C. Yue) for pointing
+out that in V0 of this document I did not properly describe the
+unused sectors normally found around the partition table sectors.
+
+/end/
+--
+\\===============\\=======================\\
+ \\ Hale Landis \\ 303-548-0567 \\
+ // Niwot, CO USA // landis@sugs.tware.com //
+//===============//=======================//