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

  1. #21

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    Id rather have a vortex86dx, a 1.5ghz 486dx! that would be sweet. I keep an eye on ebay, sometimes the SX version of the vortex shows up, the dx ones are mega expensive.

  2. #22
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    Quote Originally Posted by BloodyCactus View Post
    Id rather have a vortex86dx, a 1.5ghz 486dx! that would be sweet. I keep an eye on ebay, sometimes the SX version of the vortex shows up, the dx ones are mega expensive.
    Hey Sergey, I've flashed 0.9.4 of your micro 8088 bios and I keep getting this error on boot:

    IOCHK NMI dected. Type 'i' to ignore IOCHK NMIs, or 'r' to reboot.

    Hitting 'i' just repeats the message.

  3. #23
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    Quote Originally Posted by keenerb View Post
    Hey Sergey, I've flashed 0.9.4 of your micro 8088 bios and I keep getting this error on boot:

    IOCHK NMI dected. Type 'i' to ignore IOCHK NMIs, or 'r' to reboot.

    Hitting 'i' just repeats the message.
    It looks that something in your system keeps /IOCHK signal low. Just to be sure measure voltage on that signal (pin A1 on ISA bus - the rightmost on the component side of an ISA card).

    In 0.9.4 I enabled NMIs, that we're accidently disabled in previous BIOS versions... But you shouldn't be getting NMIs in a healthy system.

    Thanks,
    Sergey

  4. #24
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    Quote Originally Posted by sergey View Post
    It looks that something in your system keeps /IOCHK signal low. Just to be sure measure voltage on that signal (pin A1 on ISA bus - the rightmost on the component side of an ISA card).

    In 0.9.4 I enabled NMIs, that we're accidently disabled in previous BIOS versions... But you shouldn't be getting NMIs in a healthy system.

    Thanks,
    Sergey
    I measured 5v across A1 and GND (B1).

    IOCHK VOLTAGE.jpg

    PINS.jpg

    I don't THINK I should be seeing an NMI in this case.

  5. #25

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    What is involved in putting together one of these? I am good at soldering. Do you put them in an ISA backplane of some type?

  6. #26
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    Quote Originally Posted by alank2 View Post
    What is involved in putting together one of these? I am good at soldering. Do you put them in an ISA backplane of some type?
    The board uses through hole components, so it is not difficult to build.
    You would need a universal programmer to program the BIOS Flash ROM, the PIC12F629 used in the on-board AT2XT converter, and optionally a ATF16V8B/GAL16V8D SPLD. Commonly available TL866A/TL866CS programmers can do all of above.

    The board plugs into an ISA backplane, you can either get an industrial backplane (e.g. available on eBay), or you can build your own. You would also need a display adapter that can work in an 8-bit system, and some kind of disk interface card complete with matching disk drives, for example a floppy disk controller, an XT-IDE card, XT-CF...

  7. #27
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    Quote Originally Posted by keenerb View Post
    I measured 5v across A1 and GND (B1).

    IOCHK VOLTAGE.jpg

    PINS.jpg

    I don't THINK I should be seeing an NMI in this case.
    That's weird. Micro 8088 connects the ISA bus /IOCHK signal directly to the FE2010A chipset, so not too many things can go wrong there.

    I can suggest trying the following:
    1. Use a different VGA card. Some VGA ICs can generate NMIs using IOCHK in some cases (generally this is supposed to be used for emulating older graphics cards).
    2. Connect a 4.7k (or perhaps even 1k) pull-up on /IOCHK. The FE2010A should have an internal pull-up, but maybe it is not strong enough?
    3. Make sure that nothing else interferes - test with only Micro 8088 and VGA in the backplane.

    If nothing helps, I can add a "disable NMI" option in the BIOS. But I am curious what causes it in the first place.

    Thanks,
    Sergey

  8. #28
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    Quote Originally Posted by sergey View Post
    That's weird. Micro 8088 connects the ISA bus /IOCHK signal directly to the FE2010A chipset, so not too many things can go wrong there.

    I can suggest trying the following:
    1. Use a different VGA card. Some VGA ICs can generate NMIs using IOCHK in some cases (generally this is supposed to be used for emulating older graphics cards).
    2. Connect a 4.7k (or perhaps even 1k) pull-up on /IOCHK. The FE2010A should have an internal pull-up, but maybe it is not strong enough?
    3. Make sure that nothing else interferes - test with only Micro 8088 and VGA in the backplane.

    If nothing helps, I can add a "disable NMI" option in the BIOS. But I am curious what causes it in the first place.

    Thanks,
    Sergey
    My other VGA doesn't seem to work at all.

    I'll be switching to my EGA card this evening, which is what I will be using normally, the VGA was just for testing purposes.

  9. #29
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    Quote Originally Posted by keenerb View Post
    My other VGA doesn't seem to work at all.

    I'll be switching to my EGA card this evening, which is what I will be using normally, the VGA was just for testing purposes.
    EGA card does not have the NMI error. Your bios config tool reported an error updating values, but seemed to save the floppy disk config just fine.

    It boots from my floppy adapter fine, ran Ultima IV for a day or two without crashing, which is great.

    However, I see some strange behaviour.

    My machine only boots from a Magitronics floppy adapter, IF my Gotek is configured for S0 (first drive), but on the second drive connector.

    If I use an XT-IDE controller configured at C800, it can't boot from floppy drive.

    If I use an XT-IDE controller with rom at CA00, it boots, but keyboard doesn't work.

    I may have a funky floppy adapter, perhaps it has its own bios, although it doesn't appear to. My Malinov floppy adapter doesn't work at all, but I seem to have a problem with it in my Tandy also now, so I may have damaged it somehow...

  10. #30
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    Quote Originally Posted by keenerb View Post
    Your bios config tool reported an error updating values, but seemed to save the floppy disk config just fine.
    What flash IC type do you have? Do you use a SPLD or a 74*00 in your system?

    My machine only boots from a Magitronics floppy adapter, IF my Gotek is configured for S0 (first drive), but on the second drive connector.
    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....


    If I use an XT-IDE controller configured at C800, it can't boot from floppy drive.

    If I use an XT-IDE controller with rom at CA00, it boots, but keyboard doesn't work.

    I may have a funky floppy adapter, perhaps it has its own bios, although it doesn't appear to. My Malinov floppy adapter doesn't work at all, but I seem to have a problem with it in my Tandy also now, so I may have damaged it somehow...
    Possible address conflict? If you do use SPLD - how your SW3 is configured?

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