That's the sort of behaviour you get from a powered up video card when the console is redirected elsewhere, either from being set to different type, mono/color or there being a more primary video card, or since this is a servery beast, the possibility it's sent over serial or network for management, though I am not sure the 90 is that advanced. Also it could just be lacking input because the board is hung of course.

Though yah if you're getting RAM error which is probably no bottom 64k it's probably passing basic cpu, chipset tests, then goes into DMA and interrupt I think, waiting for something.... though IBMs can take 2 to 5 minutes to decide what is wrong with their config sometimes so make sure you're giving it long enough to unknot it's panties.

Ozzuneoj wrote on 2023-03-27, 03:26:

If I remove the memory card entirely or remove all of the RAM I get a 0211CZ error on screen with a blinking cursor below it.

that is normal, I mean on my model 56SX, if I remove the RAM modules, I get the exact same 0211CZ error. So, that error is actually good - it's a sight of (proper) life.

In my very small experience with PS/2 the only other errors that happen before RAM memory count is displayed are related to hard-drive:

IBM PS/2 57 SX Error 00370200 0000

In you case it sounds like it hangs between showing some error and the RAM memory count is displayed. So, you said you removed the SCSI card, but what about hard-drives connected directly to the motherboard - are there any?

mattw wrote on 2023-03-27, 10:18:

that is normal, I mean on my model 56SX, if I remove the RAM modules, I get the exact same 0211CZ error. So, that error is actua […]
Show full quote

Ozzuneoj wrote on 2023-03-27, 03:26:

If I remove the memory card entirely or remove all of the RAM I get a 0211CZ error on screen with a blinking cursor below it.

that is normal, I mean on my model 56SX, if I remove the RAM modules, I get the exact same 0211CZ error. So, that error is actually good - it's a sight of (proper) life.

In my very small experience with PS/2 the only other errors that happen before RAM memory count is displayed are related to hard-drive:

IBM PS/2 57 SX Error 00370200 0000

In you case it sounds like it hangs between showing some error and the RAM memory count is displayed. So, you said you removed the SCSI card, but what about hard-drives connected directly to the motherboard - are there any?

Thanks for the tips!

I had to move the incredibly huge power supply out of the way to check, but there are no other connections for hard drives in the system. Only the MCA SCSI card. I disconnected the floppy cable and it doesn't seem to be making a difference either.

I will let it sit for a few minutes just in case it's super slow, but it seems like it should do something at least, given how quickly it shows the memory error when the RAM is removed. EDIT: It's been sitting for a while now with no change. Definitely not doing anything.

I found a service manual...
http://ohlandl.ipv7.net/books/ps2-hmm.pdf

It says the same thing as the page I linked earlier, except it mentions that the memory test may or may not run. They point to the processor cache or processor board. There is no cache on this board, so it doesn't seem to be that, unless it is some kind of configuration error (jumpers, etc.), but I feel like they would mention that in the manual somewhere if that was the case. Seems really odd that anything would have failed related to the CPU. An Intel 486 DX2 isn't exactly an unreliable piece of hardware. Maybe one of the tantalums on the CPU board has failed open or something. I'll have to check them.

Maybe a faulty BIOS?
Do you have a way of flashing another (E)EPROM with a compatible BIOS to replace the current (E)RPROM?

Edit: Did you try other known good RAM modules?

Doornkaat wrote on 2023-03-27, 14:16:

Maybe a faulty BIOS?
Do you have a way of flashing another (E)EPROM with a compatible BIOS to replace the current (E)RPROM?

Edit: Did you try other known good RAM modules?

It could be a faulty BIOS I guess. I do have a USB programmer, but I'm not sure what type\capacity of chip to use or where to find the correct BIOS for this CPU card. The PROM on this processor card says P/N 41G96361 (C) IBM CORP, 1992 PB3R.

I checked the tantalums on both the CPU card and memory card and, while my testing methods may not be correct, none of the caps measured much differently than others. I know that in-circuit testing is never guaranteed though. I basically just checked for resistance with my DMM, then checked ESR with my ESR meter. Seems like if one had failed the numbers would be clearly higher, but they were all almost identical.

I haven't tested any other memory sticks, but it came with four sticks, all different types, and I tested each one individually and they all did the same thing.

EDIT: Also, I checked the manual and the FRU of the processor board is correct for the CPU installed, so it shouldn't be an issue of an incompatible CPU installed on the wrong board. The FRU is 92F0161, which matches the 486DX2 25/50 listing in the service manual.

EDIT2: Found the BIOS ROM image here:https://ardent-tool.com/firmware/system.html

They also mention that its 1x128K. I'll see if I have one of those on hand and I can try flashing a new BIOS. Though it seems like a less common fault... it's worth a try.

Okay, I flashed the BIOS image to another PROM and I get the same exact thing. 🙁

Do these systems generally have issues with bad capacitors? I see it has a lot of normal through-hole aluminum electrolytic caps. There are also some other small blue rectangular things that I'm not sure are capacitors. They don' look like tantalum caps... so I don't know.

Are you using the correct ram? these late mca machines used special snowflake ram, even though it is 95% standard 72-pin simms. also make sure you are putting the correct simms in the correct slots. I havent looked at my own xp90 in a while but I think it takes 2 simms at minimum and they need to be populated in ceratain slots.

In my own xp90 - I had a damn time with the memory riser boards. I would de-oxit those sockets - to turn a phrase.

I also am going to assume you dont have a second cpu board for testing?

luckybob wrote on 2023-03-27, 15:56:

Are you using the correct ram? these late mca machines used special snowflake ram, even though it is 95% standard 72-pin simms. also make sure you are putting the correct simms in the correct slots. I havent looked at my own xp90 in a while but I think it takes 2 simms at minimum and they need to be populated in ceratain slots.

In my own xp90 - I had a damn time with the memory riser boards. I would de-oxit those sockets - to turn a phrase.

I also am going to assume you dont have a second cpu board for testing?

Well, I slapped one stick of non-compatible memory to my model 35SX and it didn't prevent it from doing the RAM check and throwing some error code. IMO OP's system is behaving very strangely, because it doesn't even start to perform the check. If it fails because of "bad" RAM, I'd expect it to throw a tantrum, that is show error code and/or require setup disk after that.

CharlieFoxtrot wrote on 2023-03-27, 16:07:

luckybob wrote on 2023-03-27, 15:56:

Are you using the correct ram? these late mca machines used special snowflake ram, even though it is 95% standard 72-pin simms. also make sure you are putting the correct simms in the correct slots. I havent looked at my own xp90 in a while but I think it takes 2 simms at minimum and they need to be populated in ceratain slots.

In my own xp90 - I had a damn time with the memory riser boards. I would de-oxit those sockets - to turn a phrase.

I also am going to assume you dont have a second cpu board for testing?

Well, I slapped one stick of non-compatible memory to my model 35SX and it didn't prevent it from doing the RAM check and throwing some error code. IMO OP's system is behaving very strangely, because it doesn't even start to perform the check. If it fails because of "bad" RAM, I'd expect it to throw a tantrum, that is show error code and/or require setup disk after that.

Yeah, this is basically what I'm thinking. Also, this RAM has been in it for many years... not that that is a guarantee that it wasn't just thrown in there at some point. But the owner is more of a software guy, and not so much into constantly messing with hardware. He said it's been decades since this thing was last opened, but it was running about 16 years ago.

Thanks for the suggestions though guys. I will be posting here as well:
https://groups.google.com/g/comp.sys.ibm.ps2.hardware

Ozzuneoj wrote on 2023-03-27, 16:25:

Yeah, this is basically what I'm thinking. Also, this RAM has been in it for many years... not that that is a guarantee that it wasn't just thrown in there at some point. But the owner is more of a software guy, and not so much into constantly messing with hardware. He said it's been decades since this thing was last opened, but it was running about 16 years ago.

Thanks for the suggestions though guys. I will be posting here as well:
https://groups.google.com/g/comp.sys.ibm.ps2.hardware

These can be very demanding systems as hobby computers, but definitely worth the hassle if you accept the challenge: there is undeniable cool factor with PS/2s. If and when you get the system past the mem check and ready to boot, I'm almost sure that your struggles won't end. There is most likely a failed floppy drive, which hopefully can be fixed with a recap, because if your system BIOS requires media sense drive, you can't easily replace the drive with standard floppy and simple adapter. The media sense pinout and signaling in IBMs is completely different from regular drives and I think building adapter requires some sort of logic and I haven't seen instructions for one.

When I was looking for my first DOS retro PC years ago, I really wanted a model 90, until I realized that it is like jumping straight to the deep end of the pool before you've learned to swim. Few weeks ago I got my first PS/2, the model 35SX specifically, because it is perhaps the least quirky one: plain old ISA and IDE and pretty much only proprietary stuff is the floppy drive, which I managed to get working with recap. HDDs tend to fail in these also, but luckily you have SCSI instead of ESDI, so getting and installing a replacement shouldn't be overly difficult. There are of course modern MCA-IDE controllers available.

luckybob wrote on 2023-03-27, 15:56:

Are you using the correct ram? these late mca machines used special snowflake ram, even though it is 95% standard 72-pin simms. also make sure you are putting the correct simms in the correct slots. I havent looked at my own xp90 in a while but I think it takes 2 simms at minimum and they need to be populated in ceratain slots.

In my own xp90 - I had a damn time with the memory riser boards. I would de-oxit those sockets - to turn a phrase.

I also am going to assume you dont have a second cpu board for testing?

Welp... should have listened to luckybob. 🤣

Someone on the PS/2 Google Group gave basic diagnostic steps of removing RAM, starting with a pair and going from there. This got me to try different sticks and sure enough, the ONE stick I had settled on using is the one that is not compatible with this system. I think I know how I missed this when I was testing them the first time around. The first stick I tested and left running was the bad one, then the others I didn't test for long enough to notice that they eventually started working (it all starts out the same). After testing all four, I must have just picked up the first one and put it back in.

I will say, I would have expected memory error codes for bad or incompatible memory. I read through the step by step diagnostic charts and 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.

Anyway, the three sticks that work are 12 chip SIMMs (8MB, 4MB, 4MB), the one that didn't was a standard 8 chip 4MB SIMM that looks like any other out of an old PC.

After having it restore configuration data, and then setting the system time and date, it immediately booted into Windows 95 and is working flawlessly. These machines are super cool! I love how detailed all of the BIOS\setup menus are and it explains what it needs to do to fix problems or what I need to do. I'm sure it's got plenty of quirks, but so far I really like this thing. Biggest downside though is that with Windows 95 and some other software installed it has only 45MB of free space, and it has no sound card. Finding an MCA sound card is not likely to happen any time soon, but if I ever do, I'll definitely be throwing one in here.

So, thanks again everyone. And luckybob, I'm sorry I doubted you. 😁

Note that there's the Snark Barker MCA project to build your own soundcard.

Oetker wrote on 2023-03-27, 20:55:

Note that there's the Snark Barker MCA project to build your own soundcard.

Ah, yes I've seen that. That project is a bit involved for my skill level.

I really prefer to use original hardware, but if I ever decided to install a modern card for the PS/2 I would consider buying something like the Resound New Wave MCA. I just wish they sold them in green rather than white.

More likely, I'll just keep this around to tinker with and to use for testing MCA cards and other PS/2 hardware since I have never been able to do so in the past.

... if I ever stumble upon an MCA sound card for cheap though, it'll be going in this machine, at least for a while. 😁

IBM PS/2 era planars are very prone to develop solder micro cracks and pad rupture, specially around the IBM propietary ASICs. YT @CuriousMarc has documented how sneaky those board failures can be. Take this in account when diagnosing problem with your board.

Ozzuneoj wrote on 2023-03-27, 22:26:

... if I ever stumble upon an MCA sound card for cheap though, it'll be going in this machine, at least for a while. 😁

oh I've had a rough weekend, I really needed that laugh. Glad to hear you got it going.

I think it was nearly 20 years ago I got my 55SX and said "Hmmm maybe I'll get it an Ethernet NIC and a sound card if I ever see one cheap..." .... in the intervening period, I've bought Voodoos, 8 bit ISA soundblasters, and model M keyboards for $5, but it's still got no NIC or sound.

I mean, 10mb network cards are cheap-ish.
3com & intel based cards fetch a premium regardless of bus.

Granted, the cheap ethernet cards generally don't have rj-45. But AUI-rj45 transceivers are common enough.

Token ring is extra cheap and sometimes even free!

Ozzuneoj wrote on 2023-03-27, 18:21:

Someone on the PS/2 Google Group gave basic diagnostic steps of removing RAM, starting with a pair and going from there. This got me to try different sticks and sure enough, the ONE stick I had settled on using is the one that is not compatible with this system.

Doornkaat wrote on 2023-03-27, 14:16:

Did you try other known good RAM modules?

Just saying.🤷‍♂️😜