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IBM PS/2 MODEL 25SX 386 I picked up for free and needing some help with =D

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custm42435

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Joined
Dec 10, 2008
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Chattanooga, Tn
Hello all,
So I picked up a PS/2 model 25sx and saved it from recycle, and now trying to beef it up a bit and add it to my collection.
seems the 25SX model was a rare one, only sold to schools for education purposes so not much documentation on this particular model can be found.
It is a 386sx-20, with a 387 math co socket, has 4 meg memory on board, and one slot for additional memory, IDE hard drive interface, and 3 internal ISA slots, and VGA all packed into model 25 goodness =)
So far, I have tried every single 72 pin simms memory I have (only have 3, and one of them has ibm logo on it) and all give errors when I try turn the machine on with them, even after using the system disk to autoconfigure for them, so apparently they must not be the right kind of 72 pin for this system (anyone have any? id be willing to do some trades =) )
Current hard drive is 80 meg, although I would like to go with a much higher size, using an isa card ide controller if I have to, to be able to use a higher size and possibly even an ide-sd unit that I have (id love to use a 4 gig sd card with it)
or even the possibility of an isa controller card and run a cable out the back for maybe a cd rom? =D
today my ESS isa sound card came in the mail, I installed it, and can finally hear KQ6 with much better sound than the internal speaker

so what I need: memory,387 math co, OR 386-486 upgrade, ide controller card, and anyone elses experience and expertise on adding a much larger sized drive.
I can either pay for anything anyone has to help me, or do trading with the vast amount of hardware and items I have.

Thanks in Advance! =D
 
custm42435 said:
Hello all,
So I picked up a PS/2 model 25sx and saved it from recycle, and now trying to beef it up a bit and add it to my collection.
seems the 25SX model was a rare one, only sold to schools for education purposes so not much documentation on this particular model can be found.
It is a 386sx-20, with a 387 math co socket, has 4 meg memory on board, and one slot for additional memory, IDE hard drive interface, and 3 internal ISA slots, and VGA all packed into model 25 goodness =)
So far, I have tried every single 72 pin simms memory I have (only have 3, and one of them has ibm logo on it) and all give errors when I try turn the machine on with them, even after using the system disk to autoconfigure for them, so apparently they must not be the right kind of 72 pin for this system (anyone have any? id be willing to do some trades =) )
Current hard drive is 80 meg, although I would like to go with a much higher size, using an isa card ide controller if I have to, to be able to use a higher size and possibly even an ide-sd unit that I have (id love to use a 4 gig sd card with it)
or even the possibility of an isa controller card and run a cable out the back for maybe a cd rom? =D
today my ESS isa sound card came in the mail, I installed it, and can finally hear KQ6 with much better sound than the internal speaker

so what I need: memory,387 math co, OR 386-486 upgrade, ide controller card, and anyone elses experience and expertise on adding a much larger sized drive.
I can either pay for anything anyone has to help me, or do trading with the vast amount of hardware and items I have.

Thanks in Advance! =D
Click to expand...

Here is a nice page about it...


PS/2 simms are different than bog standard PC Simms. There is a way to convert them so the Memory Presence detection works, but it's usually easier to look for the IBM kit first.

I'm not sure that you can disable the onboard IDE, but you should look into the XT-IDE (or maybe just an added BIOS on a 16 bit ISA card for that machine) for helping add a larger drive.
 
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What is the error with the memory? Cryptic numeric codes on startup on a PS/2 does not necessarily mean there is a problem in hardware, it may just mean that the system option for whatever has been installed or removed needs to be set in the BIOS, this is done using a PS/2 reference diskette for your particular model/series of PS/2. It could just be the computer sees new RAM and needs it set in the BIOS.

With a machine like the 386, I know you can get pretty modern with hard drives providing you have Dynamic Drive Overlay software to allow the computer to see sizes beyond 528MB. My 486 has a 3GB and I'm prepping a 40GB Drive for it for example, both have a DDO, both address much lower size in the BIOS. Might be a bit pesky with a PS/2 though since they do find new hardware. I had a Model 30/286 that had a DIamond Telecommander 2300 soundcard/modem in it that worked great, but it always threw an error on bootup because the BIOS was trying to configure/add the card to the hardware listing, and that particular card did not have a PS/2 reference disk for it. Autodetect I think was created for their Microchannel Bus but it seems it also applies with ISA as well in a PS/2.

Depending on the case, a CD-ROM internally may be possible. But if you want to get around the CD-ROM, just install an ISA network card, set the computer up for TCP/IP networking in Microsoft Network CLient 3.0, share the C drive on the network, and copy what you need to it. That's how I admin all my old DOS machines.

As for the 387, I'm not sure what you are using the machine for, but DOS Gaming generally does not make much use of the Co-Processor (I think I maybe have one piece of software on my 286 that uses the 287, and that's Broderbund Jetfighter).
 
The late era Model-25sx should support 500MB drives on the built-in controller. I thought that model was after IBM made sure the IDE was what other companies were using so installing should be easy. If you can find a 512MB compact flash card, I would try that at first before going for the bigger drives.

For the CD-ROM, I would suggest looking for one of those parallel port external enclosures for IDE CD-ROMs. Not as cheap as they used to be but I think you can get one for less than $20 still. IDE cables need to be short. Long IDE cables sitting outside a case seems a great way to have massive interference and many errors on data transfer.

387 is probably going to be a waste of money. 486 depends on which model. Don't forget cooling; the 25SX case isn't designed to handle the highest power consuming 486 models. Downclocking a 486 to prevent overheating that cramped space beneath the CRT seems like a very expensive way to have a system that performs much the same.
 
Dpatten, Thanks for the info page, and glad to see my 25sx is one of the few actually running at 20 Mhz
Mad Mike, the memory errors persist even after using the reference disk to try to let it autoconfigure for the 72 pin simms I have.
Krebizfan, I would probably just go the route of getting a 486sx chip and unsoldering my 386sx and replacing, as I DO a lot of soldering and have a hot air station. and since the two chips are compatible to be swapped out.
I do not have a 500 mb hard drive, though I have DOZENS of hard drives with a capacity of 2 gig all the way to 1TB.
what I eventually want to end up with, is it handling a drive large enough to support around 4 gig of original dos and windows gaves from the era, and putting in my collection as such. I currently have a dvd with 1800 games on it, waiting for a new home to goto =D (anyone want a copy?)
 
dpatten said:
here is a nice page about it...


ps/2 simms are different than bog standard pc simms. There is a way to convert them so the memory presence detection works, but it's usually easier to look for the ibm kit first.

I'm not sure that you can disable the onboard ide, but you should look into the xt-ide (or maybe just an added bios on a 16 bit isa card for that machine) for helping add a larger drive.
Click to expand...

how would i convert them? I have a soldering iron plugged in and ready =d
 
I'm not normally one to tell people what to do with their collection, but I encourage you to keep the original 386 chip installed and get a snap-on 486 upgrade instead. If you're looking for a 486-class AIO PS/2 model with CD-ROM, Eduquests are out there and feature these things as standard. As you said, the 386sx and the even rarer Model 25-286 are quite rare. It'd be a shame to lose another one, IMO. Though, tbh, free is a good price, and Eduquests, Model 25's, and 25-286/25sx's aren't typically free :) Just my $0.02... have fun!!
 
These things if I can recall were stupid cranky about the max ram you fed it. Because it's a 386, go over 16mb and it was pretty unhappy.
What are the error codes you are getting? When the system turns on and completes the memory test it will give the codes in XXX XX or XXX format. For example:
Code: 
161

163

...means the NVRAM battery is dead and the clock is not set. In that case you can feed it the reference disk all day but it's not going to hold the configuration. Check and see if the battery is still good.
 
Maverick1978 said:
. As you said, the 386sx and the even rarer Model 25-286 are quite rare. It'd be a shame to lose another one, IMO. Though, tbh, free is a good price, and Eduquests, Model 25's, and 25-286/25sx's aren't typically free :) Just my $0.02... have fun!!
Click to expand...


Ah, I later also picked up the Model 25 286 for free to go with the Model 25 SX 386 :D Both now have sound cards installed, and the 386 runs off an 8 GB compact flash which i have filled with all the "oldie but goodie" 1980-1990's games and Windows 3.1 for a day of retro fun. both have vga monitors installed although the 286 one has some screen burn-in on the monitor from where it was used as a terminal for a VERY long time.

The 286 model 25 had this card in it.. anyone know what it is? here is a link with a pic of the exact card http://sine.ni.com/nips/cds/view/p/lang/en/nid/1238
 
Seems this is what the card does, but i still have no idea what that means lol
GPIB-PCII/IIA Hardware Overview
The GPIB-PCII/IIA interface board combines the functionality of the
National Instruments GPIB-PCII and GPIB-PCIIA interface boards. It can
be configured to function in either GPIB-PCII mode or GPIB-PCIIA mode,
depending on the setting of the configuration switches.
The GPIB-PCII/IIA board, equipped with the NAT4882 ASIC, transforms
any IBM PC, PC/XT, PC AT, or compatible computer into a
full-functioning IEEE 488.2 Talker/Listener/Controller. The NAT4882
controller chip is fully compatible with the IEEE 488.2 standard.Chapter 1 Introduction
© National Instruments Corporation 1-3 GPIB-PCII/IIA for Windows 98/95
You can use standard GPIB cables to connect the GPIB-PCII/IIA with up
to 14 instruments. If you want to use more instruments, you can order a bus
extender or expander from National Instruments. Refer to Appendix D,
Specifications, for more information about the GPIB-PCII/IIA hardware
specifications and recommended operating conditions.
 
Not that complicated. It means your system was most likely used in a science lab or similar place. Testing equipment could be controlled or logged by the computer. IEEE 488 is just another way of talking to other equipment, think very expensive parallel port. If you don't have any devices that use IEEE 488.2, the card will be completely useless.
 
krebizfan said:
Not that complicated. It means your system was most likely used in a science lab or similar place. Testing equipment could be controlled or logged by the computer. IEEE 488 is just another way of talking to other equipment, think very expensive parallel port. If you don't have any devices that use IEEE 488.2, the card will be completely useless.
Click to expand...

Yeah, maybe someone else might have a need for the card then ill just keep the computers lol
 
custm42435 said:
Ah, I later also picked up the Model 25 286 for free to go with the Model 25 SX 386 :D Both now have sound cards installed, and the 386 runs off an 8 GB compact flash which i have filled with all the "oldie but goodie" 1980-1990's games and Windows 3.1 for a day of retro fun. both have vga monitors installed although the 286 one has some screen burn-in on the monitor from where it was used as a terminal for a VERY long time.

The 286 model 25 had this card in it.. anyone know what it is? here is a link with a pic of the exact card http://sine.ni.com/nips/cds/view/p/lang/en/nid/1238
Click to expand...

How did you manage to get it to run off a compact flash card? I know this is an old thread but I'm hoping that you can tell me on which ROM and I/O address you were running the card, to avoid a conflict with the onboard IDE.
 
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