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Thread: PS/1 Consultant 2155 + XT-IDE

  1. #1

    Default PS/1 Consultant 2155 + XT-IDE

    Hi all! I'm having a bit of trouble using CF cards on my IBM PS/1 Consultant 2155-G5. I wanted to add a CF card as a second drive, so I bought a CF-to-IDE adapter but haven't had much luck getting the CF card properly recognized in DOS (the BIOS only recognizes 528 MB on a 1 GB card). I tried formatting the card on another computer to the full size, but I get read/write errors in DOS when I try to use the card. I had a similar problem on another 486-class machine which I got around using the XT-IDE BIOS on a Lo-tech ROM board. I built and tested a second Lo-tech ROM board (with the latest XT-IDE BIOS image) but I can't get the PS/1 to show the option ROM boot screen. I know the ROM card works, since I was able to test it with my other 486 machine. On the PS/1, I can read the config from the XTIDECFG utility and flash the BIOS image with Lo-tech's FLASH.EXE but I just can't get the boot screen to show up. It appears that the ROM contents are being loaded into RAM (checked with WinCheckIt), but no boot screen. Am I missing something here? Is there a better way to use the original IDE disk and a CF card? As always thanks for the advice!

    Mike

  2. #2

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    Quote Originally Posted by m1k3e View Post
    (the BIOS only recognizes 528 MB on a 1 GB card). Mike
    You're forgetting the limitation of most BIOS's of the day:

    https://www.informit.com/articles/ar...28834&seqNum=6

  3. #3

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    Quote Originally Posted by T-R-A View Post
    You're forgetting the limitation of most BIOS's of the day:

    https://www.informit.com/articles/ar...28834&seqNum=6
    Yep! Definitely seems like the case. I guess what I’m asking is can an XT-IDE option ROM allow me to use the onboard IDE controller to access a larger drive, or am I better off with a newer ISA IDE controller that supports larger disks (I found one on eBay labeled “EIDE ISA V.2” which I think might work. Any suggestions would be welcome! 🙂

  4. #4
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    Any IDE controller which supports drives larger than ~504 MB is going to require and option ROM to patch the INT13h routines in the system BIOS, which DOS calls for disk access.

    If this is the card you're talking about: https://www.ebay.com/itm/303171095328

    Then it's not going to work. It's basically a passive adapter to the ISA bus and relies on the system BIOS for drive support, putting you back where you started.

    You either need an XT-IDE card, or drive overlay software. Alternatively, some SCSI cards had their own routines for disk access and don't suffer the same limits of IDE drives. But, this puts you down the SCSI path, and older SCSI drives are getting expensive and as unreliable from age any other drive type is.

  5. #5

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    Quote Originally Posted by GiGaBiTe View Post
    Any IDE controller which supports drives larger than ~504 MB is going to require and option ROM to patch the INT13h routines in the system BIOS, which DOS calls for disk access.

    If this is the card you're talking about: https://www.ebay.com/itm/303171095328

    Then it's not going to work. It's basically a passive adapter to the ISA bus and relies on the system BIOS for drive support, putting you back where you started.

    You either need an XT-IDE card, or drive overlay software. Alternatively, some SCSI cards had their own routines for disk access and don't suffer the same limits of IDE drives. But, this puts you down the SCSI path, and older SCSI drives are getting expensive and as unreliable from age any other drive type is.
    I think I figured out my issue. I first tried putting the XT-IDE BIOS on an ISA ROM board, but it seems like the PS/1 will only load the option ROM if the hard disk isn’t attached to the onboard IDE controller (if the hard disk is attached, it boots the disk right away and option ROM never loads). There’s no option to disable the drive in the BIOS, it seems like it auto detects the drive type. I then tried a Monotech XT-IDE Deluxe that I flashed with the 386 version of the XT-IDE BIOS. I attached the drive to the IDE interface on that board and inserted a CF card (set to slave) and got everything working BUT two problems. There is about a 30 second delay when turning on the computer (seems like it’s searching for a drive on the internal interface) and, when using XT-IDE, hard disk performance really takes a dive (~100 KiB/sec vs. ~500 KiB/sec).

    I think at this point either I accept these issues or just revert to the onboard IDE controller and use a 512 MB CF card (I definitely don’t want to mess around with drive overlays). Maybe I’m wrong, but I don’t think there’s a way to get the XT-IDE to control the internal IDE interface (or at least just the CF card) since the computer won’t load the option ROM if a drive is present on the onboard IDE interface. There’s no way that the XT-IDE board would allow me to access the CF card if the option ROM never loads, correct?

  6. #6
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    I know overlays have this really bad rep, but... honestly, the couple times back in the day I found occasion to use them I remember them doing the job adequately. Even worked fine with OS/2.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  7. #7

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    Quote Originally Posted by Eudimorphodon View Post
    I know overlays have this really bad rep, but... honestly, the couple times back in the day I found occasion to use them I remember them doing the job adequately. Even worked fine with OS/2.
    I like to use the CF card to transfer files from my regular computer, would an overlay break this?

  8. #8
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    So far as I'm aware the partitions on the disk itself should be perfectly normal, there's just the hook for the overlay in the boot sector. If you're installing the CF card as a second drive you might not even have that, as the overlay's going to live on your boot drive.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  9. #9

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    Quote Originally Posted by Eudimorphodon View Post
    So far as I'm aware the partitions on the disk itself should be perfectly normal, there's just the hook for the overlay in the boot sector. If you're installing the CF card as a second drive you might not even have that, as the overlay's going to live on your boot drive.
    This really was great advice. I installed EZ-Drive 8.02W and managed to get the overlay installed on boot drive. I was able to format the full 2GB without issue. The read/write errors in DOS are gone and I can even access the card from my Windows 10 box. I had no idea it was this seamless. Thanks again for convincing me about the overlay!

    Mike

  10. #10
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    Glad it worked for you. I mean, sure, I get why people would rather not use them because they steal a little bit of conventional memory (although I believe with EZ-Drive there's a driver you can load high if you have UMBs and get it back) and you do need to be a *little* careful if you need to boot from a floppy. But they do the job for free (they used to toss a copy of EZ-Drive in with new hard disks, and despite the claim that some companies locked it to their own drives I never ran into that problem) and I remember it being capable of some interesting stupid pet tricks. I put EZ-drive on a 486 with the 512MB limit back in the day and incidentally discovered that with it loaded it would probe for and be able to recognize disks on secondary IDE channels; the BIOS could only recognize two drives. Used it to run three disks at once!
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

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