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diff --git a/etc/etc.i386/INSTALL.ata b/etc/etc.i386/INSTALL.ata deleted file mode 100644 index d0bbde7ac07..00000000000 --- a/etc/etc.i386/INSTALL.ata +++ /dev/null @@ -1,921 +0,0 @@ - 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 consuming 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 transferred. The traditional Read Sectors and Write - Sectors commands generate an interrupt to the host for each - sector transferred. - -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. However, 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 transferred. 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 transferred. 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 transferring the sector - or block or sectors. It is an "instantaneous" 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 instantaneous 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 deleted file mode 100644 index e1495877d3f..00000000000 --- a/etc/etc.i386/INSTALL.chs +++ /dev/null @@ -1,889 +0,0 @@ - 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 change the "LBA mode" setting after you have -partitioned and installed your software. - -History -------- - -Changes between this version and the preceding 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 maximum 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 addition 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 strict 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 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 - partitions. 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 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 deleted file mode 100644 index 5fc13879a5b..00000000000 --- a/etc/etc.i386/INSTALL.dbr +++ /dev/null @@ -1,467 +0,0 @@ - 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 formatting 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 - - Determine 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 sectors 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 attributes -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 deleted file mode 100644 index ebeaa0d04bf..00000000000 --- a/etc/etc.i386/INSTALL.mbr +++ /dev/null @@ -1,271 +0,0 @@ - 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 01be. - The signature is at offset 01fe. - -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 entry 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 PARTITION 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 deleted file mode 100644 index 74f6b6a4bc3..00000000000 --- a/etc/etc.i386/INSTALL.os2br +++ /dev/null @@ -1,469 +0,0 @@ - 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 restore 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 deleted file mode 100644 index 3918c992aa9..00000000000 --- a/etc/etc.i386/INSTALL.pt +++ /dev/null @@ -1,340 +0,0 @@ - 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 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 // -//===============//=======================// |