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Thread: IBM PC 5150 BIOS Versions

  1. #21

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    Thanks modem7.

    This is only possibility.

    BIOS with IBM BASIC C1.00 (BIOS - 1501476 COPR. IBM 1982 / Checksum : 00, value of FFFFh is 77h)

    --> In this case, any user may upgrade (exchange) U33 ROM chip on Rev.1 or Rev.2 motherboard.
    It is also possible to be updated with IBM PC 5150 BIOS Upgrade kit.

  2. #22
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    Has anyone done a simple binary compare of the BIOSes and tested if they differ only in the date?

  3. #23
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    Quote Originally Posted by Chuck(G) View Post
    Has anyone done a simple binary compare of the BIOSes and tested if they differ only in the date?
    Yes, I did that. Different in only the year string and in the checksum byte.

  4. #24

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    >-------------------------
    >10/19/81
    >-------------------------
    >ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
    >ROM U33 = 8K chip labeled with IBM part number of 5700671
    >ID/SUBMODEL/VERSION = FF/--/--
    >* Fixed a couple of minor display bugs.

    I've checked about "Fixed a couple of minor display bugs."
    I think it is related with font of CHR(4) on IBM PC 5150 Rev.1 (04/24/81)

    Charactor 4 Font from IBM PC 5150 Revision 1 (04/24/81)

    http://www.mediafire.com/?hx2ts944uq56ovr


    Charactor 4 Font from IBM PC 5150 Revision 2 (10/19/81)

    http://www.mediafire.com/?lfiooocq053zm2x


    I've compared two bioses from 1A6E (F000:FA6E) to 1E6D (F000:FE6D)

    Only 1 byte is different from each other at 1A95 (F000:FA95)

    Rev.1 : 08h / Rev.2 : 00h

    08h must be incorrect, 00h is right.

    I've tested in PCE (IBM 5150) emulator with Rev.1 (BASIC Mode)
    Screen is changed to 1 (40x24 mode with graphic)

    http://www.mediafire.com/?sqz9wicbxfvzfub

    A font of Character 4 must be strange.

    But if you change SCREEN 1 to SCREEN 0 (Text Mode), the font is shown correctly.

    http://www.mediafire.com/?odthb88vcs7ndb1

    I think this must be from CGA font ROM.
    Anyway, Rev.1 BIOS has a minor bug.
    But I think it is Not bad dumped, because checksum byte is correct and source code of IBM PC 5150 is shown as 08h.

    http://www.classiccmp.org/cini/files/PCBios.ASM

  5. #25

    Smile 8086 , ibm compatible

    Hi all,

    I want to build 8086 based computer with 16-bit ISA bus, compatible with IBM 5150 or 5160. this is for educational purpose only.

    Reason, 8086 is 16-bit computer, so I want it build with 16 bit ROM and SRAM. I hate swapping 8-bit data around.

    This make the design straight forward.

    QUESTION:

    Can I read BIOS from original BIOS chip in IBM 5150 and insert it to 16-bit EEPROM.
    I have 2 IBM 5150, one with cassette port and the other doesn't have it.

    IF I can't do that, is there some free BIOS which I can program into 16-bit EEPROM.

    Thank you in advance

  6. #26
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    There's no practical reason why an 8-bit BIOS won't work on a 16-bit card. But I suspect that the width of the PROM bus is going to be the least of your problems.

    In particular, You will need to observe the rigamarole that goes on when odd addresses are accessed (gate them to the lower part of the bus) to emulate the 8088 BIU operation. Look to the 5170 logic for that.

  7. #27
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    Quote Originally Posted by GOLD CHIP View Post
    Hi all,

    I want to build 8086 based computer with 16-bit ISA bus, compatible with IBM 5150 or 5160. this is for educational purpose only.

    Reason, 8086 is 16-bit computer, so I want it build with 16 bit ROM and SRAM. I hate swapping 8-bit data around.

    This make the design straight forward.

    QUESTION:

    Can I read BIOS from original BIOS chip in IBM 5150 and insert it to 16-bit EEPROM.
    I have 2 IBM 5150, one with cassette port and the other doesn't have it.

    IF I can't do that, is there some free BIOS which I can program into 16-bit EEPROM.

    Thank you in advance
    First of all to answer your question, there is the XT BIOS by Anonymous, which is as far as I can tell is pretty popular for clone XT systems.
    I wrote my own BIOS, which is IBM PC compatible, but also supports many features from AT and PS/2 (RTC, AT keyboard, PS/2 mouse, support for HD/ED floppy drives). You can find the source code and binaries here. Note that this BIOS will not work on the original PC or XT, at least because it requires AT keyboard and doesn't configure DMA to perform DRAM refresh.

    Now I would like to question your idea of building 8086 based system

    It is completely possible to build a 8086-based system with 16-bit SRAM and ROM. The memory part is the least trouble just use 2 chips to get 16-bit data width. You can also put 8-bit I/O devices without using A0 address line (using A1) instead, and use only even addresses to access them.
    But it is impossible to implement an IBM PC compatible system without implementing proper data bus steering logic. That is because in IBM PC compatible systems:
    - All the on-board I/O (Keyboard/8255 PPI, 8259 PIC, 8237 DMA, and so on) is using 8-bit data bus and steering logic will be required to access odd I/O addresses.
    - ISA cards can have 8-bit memory, and many have 8-bit I/O.

    So you have several choices here:
    - You can implement a non-IBM PC compatible 8086 system. But in this case I see little reason for using 8086 CPU (unless you happen to have one and really want to put it in use). You could use a 80186 instead, and enjoy multiple peripherals it has on the chip, or use 80286 (or perhaps even 386SX/386EX) and get a more speedy system. The IBM PC compatible BIOS will not work on such system, at least not without serious modifications.
    - You can implement an IBM PC compatible system, implementing bus steering logic (which is quite complex). There are a few IBM compatible PCs that have done that: Olivetti M24, ES1840/ES1841, IBM PS/2 models 25 and 30. I think I saw Olivetti M24 schematics on the net - and it is considerably more complicated than IBM PC one.
    - You can use 8088 processor, which makes building IBM PC compatible system much easier.

    In case you just want to build an x86 computer, you might want to check the following:
    - PC Retro kit. Basically a complete copy of an IBM PC
    - My Xi 8088 project.
    - SBC-188 project. Much more simple than previous two, yet partially IBM PC compatible (as long as the program uses BIOS/DOS API to access the hardware).
    Last edited by sergey; March 1st, 2013 at 11:20 AM.

  8. #28
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    One other consideration--if you are set on using 16-bit cards, bear in mind that these come in two flavors.

    There are those that were made to function in either 8 or 16-bit slots (several NICs and display cards)--they're okay. Then there were those that would work in 16-bit slots only (e.g. disk adapters, SCSI cards, etc.) You'll find that very often, their extension ROMs use the 80186 instruction additions and that an 8086 won't execute the code. You can, however, substitute a NEC V30 to accommodate those.

  9. #29

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    Quote Originally Posted by sergey View Post
    I think I saw Olivetti M24 schematics on the net - and it is considerably more complicated than IBM PC one.
    And not exactly correct either:
    https://groups.google.com/d/msg/comp...8/S96D5XRLeRQJ

  10. #30
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    Yeah, we "rediscovered" this 6300 quirk when trying to get the XT-CF going in 16-bit mode on a 6300--all the bytes were swapped. The answer was to conduct our 6300-to-CF traffic in 8 bit mode. Fortunately, 8 bit mode is a non-optional requirement for CF cards, unlike PATA drives.

    The 6300 bus converter logic is far from simple.

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