IBM PS/2 Model 90 XP 486, no post, no beeps, just blinking cursor.

[Ozzuneoj]

I was just given this machine by the original owner who said it worked when last powered on about 16 years ago. As the title says, when powered on it immediately goes to a black screen with a blinking cursor in the corner and never does anything after several minutes. I am very experienced with PCs but this is my first PS/2, so I have no experience with these and I have no other PS/2 parts to use to diagnose issues.

The system definitely looks like it has received upgrades over the years, but they should all be compatible since they were working years ago.

System specifics:
Front of case marked PS/2 Model 90 XP 486
Front of internal chassis marked 8590-0H9
92F0161 Processor Card with DX2 50Mhz and 41G96361 ROM
20MB (8+4+4+4) RAM on one memory card
SCSI card, SCSI hard drive and SCSI CD-ROM (all disconnected for diagnostics)
2.88MB floppy (also disconnected for diagnostics)

I have tried the following:
New CR2032 battery
removed SCSI card and removed power from drives
reinserted processor card and memory card
tried each memory SIMM one at a time
flashed new ROM image to a PROM and installed that on CPU card
Moved J10 jumper position (was on 2-3, tried on 1-2)

None of the above changed the blinking cursor on the screen, and there are no beeps. The only thing that ever changes anything is if I remove all of the SIMM memory or remove the memory card entirely, it will give a 0211CZ error and a blinking cursor (still no beep)... which tells me it is at least able to acknowledge that the RAM is there, but I have yet to see a memory test on screen at all.

Any help would be much appreciated!

[Louis Ohland]

First item of note, it is alive and the video works [to some extent]

[Louis Ohland]

Remove all MCA adapters. We are troubleshooting.

https://www.ardent-tool.com/complex/T2.html#L_486DX2-50

"L" complex, 486DX2-50, should work.

Try placing a pair of 4MB SIMMs on J11, the riser closest to the
complex. Use J1 and J3.

https://www.ardent-tool.com/90/Planar.html#Memory_Riser

The H and L can use single, paired, or mismatched SIMMs. But you are
troubleshooting. Use a universally supported configuration. Can't hurt.

Re-seat the complex. https://www.ardent-tool.com/complex/Install.html

Re-seat SIMMs into J11 riser, using J1 (A1) and J3 (B1). Make sure the
SIMMs are correctly oriented.

https://www.ardent-tool.com/complex/T3.html#H097075

https://www.ardent-tool.com/complex/Install.html

Power up. Report.

[Ozzuneoj]

Thank you for the suggestions. I just tried this just to be sure, and to my surprise something did change! One of the memory sticks (a simply 8 chip one labeled as 4MB... looks like one out of a normal PC) seems to hang the system forever at the blinking cursor. With any combination of the other three however, the monitor will actually go into standby after about 6 seconds, stay in standby for several seconds, and then I actually start to get some error codes on the screen! They are 00060100 and later 19990022... haven't looked them up yet, but they are probably related to all of the things I removed. I will try reconnecting everything and just using these SIMMs. They are, to me, a bit odd looking with 12 chips and slightly taller PCBs compared to the SIMMs found in other PCs. Thank you again! I will report back here with my findings.

[Ozzuneoj]

By the way... I think I know why this didn't turn up when I tested the memory sticks individually. I guess the first one I tested and left running was the bad one, then the others I didn't test for long enough to notice the display going into standby, because they all start out the same. Oy...

I will say, I would have expected memory error codes for bad or incompatible memory. I read through the step by step diagnostic charts before posting here and everything pointed to a processor board or cache issue. Nothing mentioned RAM problems unless there was a memory error code or beeping involved. I guess at the time it may not have been common for incorrect (but fitting) PC memory to have been installed in these systems.

[Ozzuneoj]

Success! Wow... I'm SO glad that's all it was. I hate doing board-level diagnostics, especially on systems I am totally unfamiliar with.

It is now booting to Windows 95, and running surprisingly well. Thank you for the suggestion. It's a little odd because I basically already did exactly what you said last night, I just didn't wait long enough to see if it worked. LOL

Ah... old computers. ;)

Thanks again!