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Thread: Compaq Deskpro XT restoration - help needed

  1. #21

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    I'd only been loosely aware of the dual clock speeds so I dug a bit deeper. 5:1 remains the optimal at the higher ~8MHz clock.

    IMG_0172.jpeg

    IMG_0166.jpeg

    As it turns out, when the PC boots into Compaq DOS 3.30 from the hard drive, the speed seems to reset to low (red light on front fascia) whereas a boot from a MS-DOS 5.0 floppy leaves the processor at the higher clock. So, my original first pass with Spinrite was at the higher clock speed. Does the sustained transfer rate seem low for this hardware?

    The controller is an Everex model, assembly # HH 36815, with a v3.92 Everex BIOS. I see a number of WDC ICs on the board.

    Any speculation on why this PC would have so many Everex components? In addition to the drive and controller, there is an Everex EVGA card (EV-657) and an Everex modem (EV-920). Seems like a lot of Everex hardware to find in a Compaq Deskpro... curious.

    Pending input from this forum on the drive performance, I don't plan to mess further with the drive until an XT-IDE card arrives and I can get a solid backup of the data on the ST-225. Instead my attention is turning to some of the other issues. While I do want to address the problematic B: drive, first order of business is replacing the battery (BR-2325) on the clock card... it's a Compaq Clock/Asynchronous board, assy 000061-001 (wow, low p/n for a Compaq part...) and appears to have a serial port on it. The battery spins freely and should be easy to replace if I can remove the clip w/o bending it.

  2. #22

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    I’d guess they were just an upgrade. My deskpro had floppy only with a hardcard, so I’m guessing that it was a cheaper option than going with compaq parts.

  3. #23

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    If it is booting Compaq DOS (all versions) it should automatically switch to high speed. Unless there is a utility setting it back to slow mode (I think the Compaq MODE command can do it) in AUTOEXEC.BAT. As for upgrades, Compaq charged a premium for any upgrade so it makes sense that someone would have done a third party upgrade. I have a Compaq Portable that had a Miniscribe HD upgrade. The EGA card is nice - I guess you have a matching monitor. Pretty cool.

    Your clock card can be adjusted using GETCLOCK/SETCLOCK with Compaq DOS 3.3x and CLOCK.SYS with Compaq DOS 5.0. I prefer 5.0 for no particular reason other than it's newer and supports 2 GB partitions, but both should be functional. Compaq DOS 3.31 was the last 3.3x version and is recommended (especially with an XT-IDE on the way for large disk support).

    As for your floppy, hopefully a good cleaning will help including the cable connections. I wasn't clear if you tried swapping the floppy drives around to see if anything changed. Also, DIP switch 7 sets the number of floppy drives: on = one, off = two.
    Last edited by resman; March 19th, 2020 at 12:24 PM.

  4. #24

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    Quote Originally Posted by resman View Post
    If it is booting Compaq DOS (all versions) it should automatically switch to high speed. Unless there is a utility setting it back to slow mode (I think the Compaq MODE command can do it) in AUTOEXEC.BAT. As for upgrades, Compaq charged a premium for any upgrade so it makes sense that someone would have done a third party upgrade. I have a Compaq Portable that had a Miniscribe HD upgrade. The EGA card is nice - I guess you have a matching monitor. Pretty cool.

    Your clock card can be adjusted using GETCLOCK/SETCLOCK with Compaq DOS 3.3x and CLOCK.SYS with Compaq DOS 5.0. I prefer 5.0 for no particular reason other than it's newer and supports 2 GB partitions, but both should be functional. Compaq DOS 3.31 was the last 3.3x version and is recommended (especially with an XT-IDE on the way for large disk support).

    As for your floppy, hopefully a good cleaning will help including the cable connections. I wasn't clear if you tried swapping the floppy drives around to see if anything changed. Also, DIP switch 7 sets the number of floppy drives: on = one, off = two.
    First, a mea culpa to correct something I posted earlier in the thread. This PC is not running Compaq DOS... it's running IBM PC-DOS 3.20. I was mistaking the clock.sys (clearly from Compaq DOS) that first appears on boot and flashes a banner that, if not looking closely before the CLS, and assuming Compaq OS in line with the hardware in front of me, can be mistaken. Not sure if that addresses the clock speed topic... this PC definitively boots at 4.77MHz off the HD. I agree that later on I will upgrade the OS to a more appropriate DOS.

    First thing's first, the drive. The XT-IDE came in faster than expected, and after prepping a CF card with DOS 6.22 (took some effort to get it booting) it works! I can pull up the XT-IDE boot menu, and use it to boot off floppy, the ST-225 or my CF. Now I finally had an easy way to both move data off the PC as well as push software to it.

    New issue: HD has some FAT corruption. IBM DOS 3.2 (the boot OS) chkdsk throws a half dozen errors before crapping out in one folder off the C root (c:\paint.... appears to be an 'egapaint' program). Chkdsk off my DOS 6.22 CF fully runs a scan and finds about 50 files with various errors to be fixed... scattered about various folders. Several layers of problems here. First, I can't xcopy the files off the drive because the copy craps out at many of these problem files / folder entries. So I have to fix the corrupted FAT. But, one of the first files identified as having problems is IBMDOS.COM and this makes me nervous that if I let chkdsk do its thing, I'll end up with a non-booting primary hard drive and I don't want to deal with that yet.

    I had Norton 7.0 handy and thought to give it a try (thank goodness for that CF card...) but it apparently supports 286+ PCs only. I could download an older version.

    So questions:
    1) In the meantime, any suggestions on a DOS based, XT friendly disk imaging tool? The drive is only 20MB... I'd feel a lot more comfortable knowing I have a clean image before I try to repair (then copy) the files.
    2) Once imaged for safekeeping... any suggestions on the right tool to fix the corrupted FAT? Older or newer chkdsk? Is there something that can fix/truncate all corrupted files except IBMDOS.COM so I can get a logical backup of this thing before moving forward to the next step?

    Regarding the floppy drives... The system boots and works fine with only the "working" drive connected. This is a Toshiba 360K drive that is built like an absolute beast - it's really something to behold. There's only one jumper bank on it with jumper set to D2. I then swapped it for the "not working" second drive, a Mitsubishi also well built but nothing like the Toshiba. It has a jumper bank set to D1. With that drive connected, the system did boot off a DOS 5.0 floppy but somewhat slowly. Checkit diagnostics show the drive reads disks just fine, however writes fail every time. I'm suspecting it has some issues... going to set it aside for the moment but I'd appreciate advise on the D1/D2 jumper settings in case that is causing the recognition issues when both drives are connected.

    Lastly... a very funky thing about the EGA card and display. The computer came with an old NEC Multisync monitor (beige, I think 12", color tube with monochrome toggle) and no shortage of switches. The Everex EGA 9-pin connector is very high up on the card... so much so that the video cable is blocked by the desktop chassis's upper lip above the card cage. If you press it real hard, there's just barely enough pin contact to get a signal... barely. I wonder if the previous owner lived with it that way. I was tired of it (for now) so I tried a Tseng ET4000AX card I had from another project, and to my amazement it works great! Now I have a VGA connector, no cable issues, and a lot more display flexibility. I do want to get back to the EGA card but the VGA solution will work well while I bring the rest of the system back up to speed.

  5. #25

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    Posts take some time for moderators to approve... the above note was a couple of days ago and I've made progress.

    Both floppy drives work. Motherboard switch was set to 1 drive only (strange). The Mitsubishi drive is reading/writing after being disassembled and thoroughly cleaned, lubricated.

    I also backed up the hard drive - both an image as well as a manual logical copy of as much as I could get. Some interesting apps here... EGA Paint (cool!), Dinner At Eight (recipe app) and Sierra's 3D Helicopter game. With two good floppy drives, an XT-IDE that boots, and a refreshed HD, I think it's time to drop a clean new OS on this vintage marvel... I've both Compaq DOS 3.31 and 5.0 and will need to decide which I prefer. With only 640KB RAM, it seems prudent to avoid 6.22 due to RAM, however if anyone has guidance on ways to add EMS to XT class machines such as these, I'd be game!

  6. #26
    Join Date
    Mar 2020
    Location
    Stouffville, Ontario, Canada
    Posts
    48

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    Quote Originally Posted by Bmurching View Post
    Posts take some time for moderators to approve... the above note was a couple of days ago and I've made progress.

    Both floppy drives work. Motherboard switch was set to 1 drive only (strange). The Mitsubishi drive is reading/writing after being disassembled and thoroughly cleaned, lubricated.

    I also backed up the hard drive - both an image as well as a manual logical copy of as much as I could get. Some interesting apps here... EGA Paint (cool!), Dinner At Eight (recipe app) and Sierra's 3D Helicopter game. With two good floppy drives, an XT-IDE that boots, and a refreshed HD, I think it's time to drop a clean new OS on this vintage marvel... I've both Compaq DOS 3.31 and 5.0 and will need to decide which I prefer. With only 640KB RAM, it seems prudent to avoid 6.22 due to RAM, however if anyone has guidance on ways to add EMS to XT class machines such as these, I'd be game!
    Been following this thread and you calling the machine a vintage marvel seems spot on.

    The most straightforward way of getting EMS on the machine would be to add it via card. Since it's an XT you can get away with an 8-bit card and I've seen a couple of those on ebay from time to time and they seem to be a bit less than a 16-bit card for the most part.

    Now, unless you have a specific application that needs EMS there may be no point in adding it. You'll also need to install an EMS driver which will take some more conventional memory, and I don't think there is really any way you could use that memory to load drivers high or anything like that. You could put a RAM Disk or a cache in there, but again that would take even more conventional memory. Still, if you want to add it I say go for it! That's the fun with all this vintage stuff.

    Oh, and I'd go with 3.31 simply due to memory use.

  7. #27

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    Quote Originally Posted by Bmurching View Post
    Posts take some time for moderators to approve... the above note was a couple of days ago and I've made progress.

    Both floppy drives work. Motherboard switch was set to 1 drive only (strange). The Mitsubishi drive is reading/writing after being disassembled and thoroughly cleaned, lubricated.

    I also backed up the hard drive - both an image as well as a manual logical copy of as much as I could get. Some interesting apps here... EGA Paint (cool!), Dinner At Eight (recipe app) and Sierra's 3D Helicopter game. With two good floppy drives, an XT-IDE that boots, and a refreshed HD, I think it's time to drop a clean new OS on this vintage marvel... I've both Compaq DOS 3.31 and 5.0 and will need to decide which I prefer. With only 640KB RAM, it seems prudent to avoid 6.22 due to RAM, however if anyone has guidance on ways to add EMS to XT class machines such as these, I'd be game!
    Depending on how big your CF card is, DOS 5.0 will get more use out of it. I've found Compaq's DOS 5.0 to be a nice sweet spot between memory usage and functionality. If you ever get a NEC V30 CPU upgrade, you can run the Iomega ZIP utilities.

    EMS is a mixed bag on this machine with a XTIDE. I have a 2MB Intel AboveBoard jumpered for 8 bit operation and set up as a RAM disk for temporary files when compiling, but really an XTIDE with CF card is just as fast. A drive cache wouldn't buy anything for the XTIDE but would be useful for your boot drive. I don't really run any other apps that take advantage of EMS, YMMV.

  8. #28

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    It's been a while since I last posted (covid -> work from home -> a lot of work lately) but I was able to spend some time this weekend working on the computer. It's in great shape now!

    Updates
    - both floppy drives and the hard drive are working perfectly
    - I was able to Dremel away enough of the housing of the 9-pin RGB connector cable to allow it to fit flush against the Everex EVGA cable. So, back to EGA goodness!
    - A second ST-225 I ordered a few weeks ago (as a backup in case I couldn't fix the original) finally arrived. I couldn't salvage any data off it--if there was any--but a low level format brought it to life as well. If I can find the extra cables, rails and faceplate, perhaps I can set it up as a second drive...?

    Next steps:
    - A new clock battery should show up within a couple of days. Once the clock is up and running, I would consider core functions 100%.
    - The mouse that came with the system (3-button "PC Mouse" w/serial connection and what looks like laser pickup?) has not been working but I haven't looked into it much yet.
    - The speaker appears to be dead - I haven't been able to get a beep out of it. I don't see any obvious BIOS or other "speaker off" setting so I am suspecting it's dead. Suggestions on (a) troubleshooting it (b) a replacement would be appreciated. The speaker appears to use a 4-pin connector connecting to a post on the motherboard with three (of four) standing pins.
    - What is a reasonable period correct [8-bit] ISA sound card for this era of computer? Not having any sound at all is disappointing--getting a speaker beeping will be nice, but even nicer would be an early sound card...
    - Looking for suggestions on any good EGA apps. I found an EGAD! demo (fractal landscape pic below) and some games. The original PC came with "EGA-Paint 2001" but the program doesn't function due to some sectors being corrupted; I'd like to find a copy...

    Some pics:

    IMG_3996.jpegIMG_4001.jpegIMG_4005.jpegIMG_4009.jpeg

  9. #29

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    Looks great!

  10. #30
    Join Date
    Mar 2020
    Location
    Stouffville, Ontario, Canada
    Posts
    48

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    The closest to a period correct sound card would be an original AdLib in my opinion, but that's certainly going to cost you based on prices as they are.

    If you don't mind a reproduction one they seem to be readily available for not too much.

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