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My Vintage Computer Virtual Museum and blog page.

IBM PS/2 Model 25 (8525) “8086”

My IBM PS/2 Model 25 (added to my collection in 1997)

  • NEC V30 – 8mhz (originally Intel 8086)
  • 640kb RAM
  • 400MB SCSI (on IBM FRU’d Future Domain TMC-841 card with BIOS)
  • SMC 8Bit 10Base-T NIC
  • Mono MCGA graphics (320×200@8bit, 640×480@1bit)
  • MS-DOS 6.22 and Windows 3.0

I went with SCSI card and SCSI Hard drive since there are only two ISA expansion slots, The SCSI card gives the possibility of external SCSI expansion (more HDs, CD, Jaz, etc…)

I need to update the photos, they still show the 20MB ISA HardCard in place instead of the SCSI controller, and the 2nd floppy drive where the SCSI hard drive now resides.  I have also tapped the power supply lines to the motherboard to add a Molex power connector for the hard drive.



10 Comments

  1. Lorenzo says:

    Hey man, I’m curious, how did you do this?

    >> I have also tapped the power supply lines to the
    >> motherboard to add a Molex power connector for the hard drive.

    Thanks,
    Lorenzo

    • Ryan says:

      I probed the power wires with a multimeter and found which ones were +5V, +12V, and ground and tapped them and added a 4 pin molex to power the drive. When I have some free time, hopefully in the next few weeks, I will add some detailed photos of the mod.

  2. Matt says:

    Hi, I have the same PC, a model 25 with a siemens 8086 and 640kb of memory, its hard drive died (it finds its controller card but not the hard drive), I’m wondering if you had any trouble installing windows on it, since in the box of windows 3.0 (with 720kb floppys in it) says it requires a 286 or higher, and is extracting power from the psu necessary with the hardcard?

    • Ryan says:

      I’d suggest an XTIDE card, and then a Compact Flash memory card (with a $0.99 IDE>CF adapter) as storage, that’s my preferred method these days, a lot more reliable than any ancient 8-bit hard drive.
      Yes, Windows 3.0 will install on a Model 25 with some caveats, the MCGA/VGA video drivers need SOME 286 instructions, this can be worked around by installing an “NEC V30” CPU in the model 25, it’s not a 286 upgrade, and won’t speed things up much, but it’s just enough to trick some things into working. With the stock 8086 CPU you should still be able to install, however, you would be limited to CGA graphics.

  3. Michael says:

    Hello,

    I bought one of these, maybe 20 years ago. I pulled it out this afternoon, still boots, a few errors I’m working out, but boots right into BASIC afterwards.

    Anyway, I mine says on the IBM label on the front, it’s a 286, not an 8086. I was just curious, if you know of any history for this machine? I’m really curious about it. Says 1989 on the back. Seems a little late in the game for a 286 but could be wrong.

    Also looking for a manual, but I’ve yet to look around. I need to change the CMOS battery, that’s one of the errors I’m getting. But I’m not sure how to get into it. Looks like the bottom slides off?

    Thanks for any info!

    • Ryan says:

      Yeah, these came in both 8086 and 286, also came in B&W or color. Yes, they were very late in the game for 8086 and 286 machines, they were a low cost machine (by IBM standards). The 8086 model doesn’t have a CMOS battery (it’s more or less an XT clone), but yeah, the 286 variant does, and I believe it’s soldered to the ISA riser board. The case bottom flips open, its on a hinge, should just be 2 screws on the back, then it slides a little and swings out.

  4. Marco says:

    Hi Ryan and thanks for sharing. I wanted to ask you if you could tell me the model of the 1.44 floppy you use and if the connection uses EDGE or PIN. I have a ps/2 model 30 8086 and I would like to go from a 720k floppy to 1.44k. Grazie, ciao.

    • Ryan says:

      You’re welcome! I would have to go back and check exactly which model, I know it’s one with the edge connector, it’s NOT being recognized as 1.44MB, it’s still only working as a 720kb drive, however I do know there is a certain model drive that supposedly will work at 1.44MB, but it’s one that has the mismatched small-button eject.

  5. shawn says:

    hello i see you mentioned xt-ide i recently bought one of those cards and installed it in my machine
    model 25 with nec chipset
    the xt-ide i bought has the boot rom in it
    and when i boot the machine
    it sees the xt-ide card but never recognizes
    any cf i put in it i have tried every dip switch setting i could think of so i put back to factory default and when it boots keeps telling me none for master and slave in the xt-ide boot bios… do i have to run the ibm ref disk and initalize the chip like i do if i put a new hard drive in it or is somthing special needed for the xt-ide card that i did not purchase

    • Ryan says:

      Have you run the XTIDE configuration utility to be sure it’s looking on the correct I/O address for the IDE port? Also they can be picky about CF cards, I’ve had the best luck with older Sandisk cards (like 512MB-2GB-ish in size). You do not need any reference disk or BIOS config or anything on the Model 25 since it’s an XT class machine, the only config you would need to worry about is the XTIDE itself.

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