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Thread: XT-IDE-equipped PC XT will not boot or recognize MFM drive

  1. #1
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    Default XT-IDE-equipped PC XT will not boot or recognize MFM drive

    So. My XT-IDE works now, with a CF card and all.
    Except when I've got my ST-225 in there at the same time. At which point it doesn't. At all. Boot menu pops up, and looks like this:
    Attachment 53457
    If I boot from the first "foreign hard disk" entry we get this:
    Attachment 53458
    ...aaaaand nothing. The hard drive shows about a second of activity, round about how much it'd use to boot to DOS, then stops, and never resumes and the screen never does anything else
    I have to flip the switch off and back on to get the PC responsive again.
    If I select the second, it gives this:
    P1130557.jpg

    And of course the compactFlash doesn't boot, because it's not a bootable disk. No surprise there.
    Booting from floppy and ROM bios both work fine, but I cannot access EITHER disk (CF nor MFM) through DOS.

  2. #2
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    Have you plugged the XT-IDE together with the MFM-Controller+ST225 in the same machine?

    This doesn't work without setting the XT-IDE as a secondary controller.

  3. #3
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    Quote Originally Posted by 1ST1 View Post
    Have you plugged the XT-IDE together with the MFM-Controller+ST225 in the same machine?

    This doesn't work without setting the XT-IDE as a secondary controller.
    I have. It only doesn't work when both are installed at once.

    And how would one set the XT-IDE as a secondary controller?

  4. #4
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    I have an XT-IDE card coexisting with an MFM controller in one of my XT clones. As an experiment, I tried the same thing in my IBM 5150 and 5160, and as expected, it worked.

    Details in the 'Coexistence with MFM hard drive controller card' section of [here].
    In that section, pay attention to the two "IMPORTANT:" notes.

    Quote Originally Posted by 1ST1 View Post
    This doesn't work without setting the XT-IDE as a secondary controller.
    Quote Originally Posted by Nevets01 View Post
    And how would one set the XT-IDE as a secondary controller?
    In my setup, I did not need to change the configuration of anything. My bog-standard MFM controller and VCF XT-IDE controller do not resource conflict. At power-on of the computer, the motherboard's POST executes the BIOS ROM (at the default address of C8000) on the MFM controller, then executes the BIOS ROM (at the default address of D0000) on the VCF XT-IDE controller.

    I did nothing special. First, without the VCF XT-IDE controller fitted, I had the machine booting from the MFM controller/drive combination. Then, I removed the MFM controller, added the VCF XT-IDE controller and CF, and got the machine booting from the VCF XT-IDE controller and CF. Then, I added the MFM controller back into the computer.

  5. #5
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    Quote Originally Posted by modem7 View Post
    I did nothing special. First, without the VCF XT-IDE controller fitted, I had the machine booting from the MFM controller/drive combination. Then, I removed the MFM controller, added the VCF XT-IDE controller and CF, and got the machine booting from the VCF XT-IDE controller and CF. Then, I added the MFM controller back into the computer.
    So, I did this. Took me a bit for various un-computer-related reasons, but the problem persists. Both drives are bootable, and each will boot when the other is not installed, but neither drive will not boot if the XT-IDE is installed, even with nothing plugged into the IDE slot.

    I think it may be a problem with my MFM controller or drive; I uninstalled it, and installed my HardCard 20 instead. Both the (bootable) HardCard and the CompactFlash booted completely fine, and both were entirely accessible:
    Attachment 53555 Attachment 53556 Attachment 53557

    I could just migrate to the HardCard, but I'd rather use that one in my Compaq Portable, and I quite like the look of the ST-225 faceplate and the sound of it spooling up and down

    I've also taken out all other cards, besides the two drive controllers and the floppy and one video/RAM card.

  6. #6
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    On face value, it sounds like there is a [resource conflict] between the MFM controller and XT-IDE card.

  7. #7
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    Quote Originally Posted by modem7 View Post
    On face value, it sounds like there is a [resource conflict] between the MFM controller and XT-IDE card.
    I think I agree. After some experimentation, it appears to be a ROM conflict: when I disable the ROM BIOS of the MFM controller, the XT-IDE gains functionality, and when I disable the ROM BIOS of the XT-IDE, the MFM controller gains functionality. When I hooked up the HardCard and the MFM together, it gave me a "ROM conflict C800" error. However, no such error occurs with the XT-IDE and the MFM. Does this mean no address conflict? How would I go about de-bugging such an issue?

  8. #8

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    Hmm. Can you still boot from floppy ? If so, I'd run CheckIt! and have a look at the memory overview.
    Perhaps the XT-IDE Universal BIOS and the MFM Controller's ROM occupy the same load address..
    "Time, it seems, doesn't flow. For some it's fast, for some it's slow.
    In what to one race is no time at all, another race can rise and fall..." -The Minstrel

  9. #9
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    Quote Originally Posted by Nevets01 View Post
    When I hooked up the HardCard and the MFM together, it gave me a "ROM conflict C800" error.
    A conflict is exected.
    Your 'MFM controller' and HardCard are sure to be standard type MFM controllers, using the resources shown in the top row of [here].
    Put them together in the same system, and you will have more than just the ROM's (both at C8000) conflicting.

    The XT-IDE is a 'different animal', in that in its default configuration, the BIOS ROM starts at D0000, and the I/O ports start at 300. It does not use an interrupt nor DMA.

    Quote Originally Posted by Nevets01 View Post
    However, no such error occurs with the XT-IDE and the MFM. Does this mean no address conflict?
    In most cases, you will not be told of an address conflict. I was surprised to hear that you saw a "ROM conflict C800" error. If an error message is presented at all, it is usually something like, "C8000 ROM ERROR", due to part of one ROM 'overwriting' the other in memory space, resulting in what the computer's POST sees as a corrupted ROM.

    Quote Originally Posted by Nevets01 View Post
    How would I go about de-bugging such an issue?
    One by one, for the three cards, confirm that their respective [BIOS ROM's] are where you expect:
    'MFM controller': starting at C8000
    HardCard: starting at C8000
    XT-IDE: starting at D000

    One way of confirming the address where a BIOS ROM starts at is to use DOS' DEBUG program. For example, I have a Western Digital WD1002-27X controller. I expect that its Western Digital BIOS ROM starts at C8000. Via the DEBUG command shown below, I can see that the BIOS ROM is indeed at C8000 (C800:0)


  10. #10
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    Following on from my previous post, BIOS ROM overlapping sometimes needs to be considered. So, BIOS ROM's starting at different addresses, but one ROM extends into the address space of the other. An example of a VGA card's BIOS ROM overlapping with the BIOS ROM on an XT-class computer, is at [here].

    But it seems unlikely to me that the BIOS ROM in your 'MFM controller' extends all the way up into the address space starting at D0000. With only the 'MFM controller' fitted, what does DEBUG show at D0000 ?

    What is the make/model of this 'MFM controller' ?

    BTW: When I click on any of your attachments (e.g. "Attachment 53557"), I see an, "Invalid Attachment specified" error.

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