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Thread: IBM PS/2 Model 70 Fixed Disk Adapter Technical Reference

  1. #1

    Default IBM PS/2 Model 70 Fixed Disk Adapter Technical Reference

    Does anyone have the technical reference manual for signals needed to interface with the DBA hard drive connector on the model 70? (would also apply to 50z and 55sx I believe). I'm running running a 70 with 2 memory expanders and a XGA card. Ideally would rather just shim in a ARM/FPGA to SD card rather than waste a slot on a scsi adapter. Currently running a Jaz drive off the parallel port, but I don't think OS2 would play well with that setup.

  2. #2

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    Isn't DBA just a modified Microchannel slot pinout? Sorta like the MCA equivalent of IDE (which is basically ISA with I/O addresses decoded and condensed to 3 pins and one IRQ line).

  3. #3

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    yes, but I believe it uses encoding similar to the st412r using MFM RLL 27. also according to the model 70 ref doc I have address lines 12,14,15 and the ones that are active. I'm assuming that's what the I/O has been condensed down to, but not sure how to decode that. been trying to find a technical reference to make sense of it.

  4. #4

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    Quote Originally Posted by seeker010 View Post
    Does anyone have the technical reference manual for signals needed to interface with the DBA hard drive connector on the model 70? (would also apply to 50z and 55sx I believe). I'm running running a 70 with 2 memory expanders and a XGA card. Ideally would rather just shim in a ARM/FPGA to SD card rather than waste a slot on a scsi adapter. Currently running a Jaz drive off the parallel port, but I don't think OS2 would play well with that setup.
    Mission's a secret, destination's unknown...

    8573-P70, 8550z, 8555sx, 8570 -AND- TAA-DAA the 8590-402!

    http://ps-2.kev009.com/ohlandl/8573/8573-P70.html
    S68X-2377-00 IBM Personal System/2 Model P70 Technical Reference Apr 1989
    P70 Supplement for the Hardware Interface and BIOS Interface Technical Reference
    DASD Storage Interface Specification Micro Channel (REV 2.2)

    http://ps-2.kev009.com/ohlandl/9590/...90_Type-0.html

    It would be uber-geek to add 1GB via DBA-ESDI.

  5. #5

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    Thanks! this is very helpful. I think I may be on to something, at least in my head. Does anyone know where I can get a custom pcb made (for cheap) that has the right pitch for the edge connector? I need the I/O connectors changed to pins, and the power/ground routed to a standard 4 pin power plug. Wouldn't mind if someone created the design


    Quote Originally Posted by ardent-blue View Post
    Mission's a secret, destination's unknown...

    8573-P70, 8550z, 8555sx, 8570 -AND- TAA-DAA the 8590-402!

    http://ps-2.kev009.com/ohlandl/8573/8573-P70.html
    S68X-2377-00 IBM Personal System/2 Model P70 Technical Reference Apr 1989
    P70 Supplement for the Hardware Interface and BIOS Interface Technical Reference
    DASD Storage Interface Specification Micro Channel (REV 2.2)

    http://ps-2.kev009.com/ohlandl/9590/...90_Type-0.html

    It would be uber-geek to add 1GB via DBA-ESDI.

  6. #6

    Default

    I think I have devised a strategy with the IBM documentation and it seems reasonably doable, but wouldn't mind some forum help.
    Code:
    1) create a gold finger pcb that connects to the DASD or 16 bit MCA slot (need to find a source for a cheap one to do dev work on. Any ideas?)
    2) connect control lines to MCA microcontroller; I know of the P82C612. Are there any others?
    3) connect data/address/book keeping pins to GPIO pins of FPGA, with necessary pull up resistors on the right lines (maybe the Spartan ones with 100+ GPIO pins @ 100MHz)
    4) program FPGA to translate IO signals to SD card or CF card via SATA->SATA-IDE bridge (unless someone knows of any IDE microcontrollers for sale)
    
    need some more documents and help for the below:
    5) create audio processing code for FPGA
    6) connect to OPL3
    7) write FPGA code for wavetable synthesis and uploading/storing of Sound Fonts in ROM and RAM
    8) connect to AC97 codec with integrated DAC/ADC
    9) port MCA microcontroller logic to FPGA software so there's no reliance on legacy parts
    10) ...
    11) profit

  7. #7

    Default

    A PCI prototyping PCB with the edge connector cut down to size will likely work for MCA prototyping.

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