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Thread: Project: Micro 8088 - Chipset-based 8088 XT compatible processor board

  1. #31
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    Quote Originally Posted by sergey View Post
    What flash IC type do you have? Do you use a SPLD or a 74*00 in your system?



    If I recall correctly in IBM PC/XT/AT (pretty much everywhere after IBM PC), the floppy drives are always configured as S1, and due to the twist on the floppy cable, the drive after the twist is selected as the first unit, and the drive before the twist as the second unit.
    Configuring drive as S0, and connecting it before the twist will make it a first unit....



    Possible address conflict? If you do use SPLD - how your SW3 is configured?
    I am not using SPLD currently; just the 00 chip. The flash is a SST39SF010A chip, the same physical chip I used on my xi8088. I just reflashed with micro8088 bios.

    I'm going to append the XT-IDE ROM to the end of the Mini8088 bios and see if that helps. I know that the Lotech xt-ide adapter I'm using uses port 300h - 31Fh, could that be causing an issue?

  2. #32
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    Quote Originally Posted by keenerb View Post
    I am not using SPLD currently; just the 00 chip. The flash is a SST39SF010A chip, the same physical chip I used on my xi8088. I just reflashed with micro8088 bios.
    Saving configuration (which does in-system Flash ROM reprogramming) only works with SPLD. This is because FE2010A by itself only generates /ROMCS for read cycles (not for write cycles). The SPLD implements its own /ROMCS, which gets activated for either read or write cycles.
    By default the configuration is set to first drive - 1.44 MB, second drive - none.


    I'm going to append the XT-IDE ROM to the end of the Mini8088 bios and see if that helps. I know that the Lotech xt-ide adapter I'm using uses port 300h - 31Fh, could that be causing an issue?
    Clarification: I meant memory address conflict, not an I/O address conflict. Can you please check that your XT-IDE extension ROM addresses do not conflict with the floppy controller BIOS?

    Is this picture similar to your floppy drive adapter?
    If so, it does have an 8 KiB BIOS, and there is a jumper (BIOS ADDR - center left) that selects either 0CA000h (to 0CBFFFh) or 0CC000h (to 0CDFFFh) as the BIOS extension ROM addresses.

    If I am not mistaken XT-IDE has a 32 KiB ROM, so that, if configured at 0C8000h, it will take all the addresses till 0CFFFFh, and will conflict with the floppy adapter above. In this case, the XT-IDE should be reconfigured to use another address (e.g. 0D0000h) for the BIOS extension ROM.

    If you do want to add XT-IDE BIOS to the Flash ROM, you'll need to put it in the beginning of the image - replace first 8 KiB or whatever the XT-IDE BIOS extension size is of the BIOS image with XT-IDE code. Something like that:
    0F0000h - XT-IDE BIOS (up to 32 KiB)
    0F8000h - BIOS configuration area (16 KiB - filled with 0FFh by default).
    0FC000h - BIOS code (16 KiB)

    If needed, I can send you a pre-built image.
    Last edited by sergey; December 12th, 2017 at 06:38 AM.

  3. #33
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    Quote Originally Posted by sergey View Post
    Saving configuration (which does in-system Flash ROM reprogramming) only works with SPLD. This is because FE2010A by itself only generates /ROMCS for read cycles (not for write cycles). The SPLD implements its own /ROMCS, which gets activated for either read or write cycles.
    By default the configuration is set to first drive - 1.44 MB, second drive - none.




    Clarification: I meant memory address conflict, not an I/O address conflict. Can you please check that your XT-IDE extension ROM addresses do not conflict with the floppy controller BIOS?

    Is this picture similar to your floppy drive adapter?
    If so, it does have an 8 KiB BIOS, and there is a jumper (BIOS ADDR - center left) that selects either 0CA000h (to 0CBFFFh) or 0CC000h (to 0CDFFFh) as the BIOS extension ROM addresses.

    If I am not mistaken XT-IDE has a 32 KiB ROM, so that, if configured at 0C8000h, it will take all the addresses till 0CFFFFh, and will conflict with the floppy adapter above. In this case, the XT-IDE should be reconfigured to use another address (e.g. 0D0000h) for the BIOS extension ROM.

    If you do want to add XT-IDE BIOS to the Flash ROM, you'll need to put it in the beginning of the image - replace first 8 KiB or whatever the XT-IDE BIOS extension size is of the BIOS image with XT-IDE code. Something like that:
    0F0000h - XT-IDE BIOS (up to 32 KiB)
    0F8000h - BIOS configuration area (16 KiB - filled with 0FFh by default).
    0FC000h - BIOS code (16 KiB)

    If needed, I can send you a pre-built image.
    If you could provide a pre-built image that would be very helpful, thanks. This thing is pretty solid other than this xtide weirdness.

  4. #34
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    Also, MSD seems to think I have 64mb of extended memory?

    Is this anything to be concerned about, or just some sort of weird msd thing?

    Attachment 42432

    And floppy drive selection goes from 1,2,3,4 to 6. Should there be a drive type 5?

    floppy.jpg

  5. #35
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    Quote Originally Posted by keenerb View Post
    Also, MSD seems to think I have 64mb of extended memory?

    Is this anything to be concerned about, or just some sort of weird msd thing?
    MSD is wrong... Extended memory can't possibly exist in 8088/V20. But I will check if there is something in BIOS that gets it confused.


    And floppy drive selection goes from 1,2,3,4 to 6. Should there be a drive type 5?

    floppy.jpg
    That's normal. IBM used type 5 for 2.88 MB drives, everyone else used type 6...

  6. #36
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    No change in behaviour.

    XT-IDE adapter installed, 128MB or 16GB cf card installed, does not recognize card and will not boot from floppy drive.

    With the CF to IDE adapter still installed but card itself removed, boots normally.

    Is this an old XTIDE build? I seem to remember having an issue with the xtide build included with the xi8088 bios you had for download at one pointn.

  7. #37
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    Quote Originally Posted by keenerb View Post
    Is this an old XTIDE build? I seem to remember having an issue with the xtide build included with the xi8088 bios you had for download at one pointn.
    Possibly... I don't remember if I ever updated the XT IDE image.
    Will get a newer image and test it tonight

  8. #38
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    Still no go. System is unusable with either of my lotech xt-ide CF adapters installed. Runs fine from just floppy, so I am really suspecting it's a problem with my adapters and not the cpu board.

  9. #39

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    Would something like this work for this:

    https://www.ebay.com/itm/IEI-4-Slot-...UAAOSwY3BZEyij

  10. #40
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    Quote Originally Posted by alank2 View Post
    Would something like this work for this:

    https://www.ebay.com/itm/IEI-4-Slot-...UAAOSwY3BZEyij
    That's the exact backplane I am using right now. Should be perfectly fine.

    Gives you room for the Micro8088, a floppy adapter, a hard disk adapter, and a sound card.

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