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linuxlove
March 21st, 2010, 11:20 AM
I've head blurbs here and there about a 386 upgrade for PS/2 Model 25. I just want to know if these even exist?

kishy
March 21st, 2010, 12:24 PM
Yeah, there were replacement system boards. I think Reply was the company name for one of them

TH99 has a couple listed.

Finding one...that'll be a different story.

IBMMuseum
March 21st, 2010, 09:14 PM
I've head blurbs here and there about a 386 upgrade for PS/2 Model 25. I just want to know if these even exist?

Usually the CPU-only approach had to start from the 286-based Model 25. Intel and Kingston made 386SX daughtercards that would work in the Model 25 286. Kevin is right that there was also planar replacements from Reply and PC Enterprises (to a 486DX4-100 or AMD 133MHz level).

Best place to research the options is William Walsh´s pages: http://walshcomptech.com/ps2/25-upgrade.htm

http://walshcomptech.com/ps2/25reply.htm

http://walshcomptech.com/ps2/kingston.htm

Anonymous Freak
March 21st, 2010, 10:05 PM
I know they existed, because I had one!

I remember the insanity of installing a late beta of OS/2 2.0 on that system. It had the 386SX-20 upgrade, 4 MB RAM, and a 40 MB hard drive. I managed to shoehorn OS/2 in there somehow. I didn't have any HD space left over for anything useful, including the Windows 3.0 compatibility layer. But I did get to 'play around' with OS/2 before most people. And it was remarkably usable on that machine.

IBMMuseum
March 22nd, 2010, 10:12 AM
I know they existed, because I had one!

I remember the insanity of installing a late beta of OS/2 2.0 on that system. It had the 386SX-20 upgrade, 4 MB RAM, and a 40 MB hard drive. I managed to shoehorn OS/2 in there somehow. I didn't have any HD space left over for anything useful, including the Windows 3.0 compatibility layer. But I did get to 'play around' with OS/2 before most people. And it was remarkably usable on that machine.

I'm thinking that sounds like a stock 25SX. The 286-based Model 25 could have a 386SX-20 daughtercard, but the proprietary drives for the lower-level Model 25s and 30s topped out at 30Mb (the 25SX had an IDE interface, with the size of the drive commonly what you describe). It is also possible to run 4Mb planar RAM on a 25 286 (independant of the CPU upgrade), but that would be very rare IBM proprietary (a few pinout lines were switched from the later standard) 30-pin SIMMs on that model (the 25SX had generic 72-pin SIMMs, with a 4Mb configuration being common).

The 25SX was supposed to be released as a 386SX-16, but there are mixed-in units, not marked externally in any way, that had 20MHz CPUs and crystals. There were also two reverse-mount NICs (one Token Ring, the other Ethernet) designed for the 25SX. I've got a couple of my units configured with more RAM and larger IDE drives, nice network-enabled all-in-one systems.

I've also got the Reply and PC Enterprises planars in a couple units too, and oodles of the stock 8086-based Model 25s...

linuxlove
March 22nd, 2010, 02:06 PM
Now is there any chance of getting one of these?

vwestlife
March 22nd, 2010, 02:27 PM
IBM also built a series of "Eduquest" PCs in PS/2 Model 25-style cases, although I don't think the motherboard from one can be easily retrofitted into a real Model 25.

Here's a video of an Eduquest 30, with a 25 MHz 386SLC (?) and a very loud built-in speaker:

http://www.youtube.com/watch?v=ePS5bBJfKZ4

Anonymous Freak
March 22nd, 2010, 04:02 PM
I'm thinking that sounds like a stock 25SX.

Ah, now that you mention it, and I did a bit of quick searching, it was a Model 30-286, not a 25. I was confusing the two models. And I know it was a native 286, not 386SX because I bought and installed the upgrade myself with my hard-earned high-school-job money, just so I could install OS/2!

(I had forgotten that the 25 was the model with the built-in monitor. I thought that the 30-series was part of the MCA branch, and that the 25-series were the ISA models in that chassis, not a separate chassis.)

IBMMuseum
March 23rd, 2010, 10:38 AM
Ah, now that you mention it, and I did a bit of quick searching, it was a Model 30-286, not a 25. I was confusing the two models. And I know it was a native 286, not 386SX because I bought and installed the upgrade myself with my hard-earned high-school-job money, just so I could install OS/2!

(I had forgotten that the 25 was the model with the built-in monitor. I thought that the 30-series was part of the MCA branch, and that the 25-series were the ISA models in that chassis, not a separate chassis.)

Ultimately it was the same system planar as a Model 25 286, there are two equal variants that were used interchangably in the 25 286 and 30 286. The Model 30 286 has a three slot riser, the Model 25 286 has a two-slot riser (the 25SX didn't have an equivalent on the Model 30 side, and had two regular ISA slots on the riser, and an additional reverse-mount ISA slot designed to fit either one of the NICs). PS/2 Models below 50 are not microchannel units (usually ISA, although there are a few laptop and notebook within that portion of the series).

It would have been the Intel upgrade (an Intel 386SX-20 CPU daughtercard, and paired ISA RAM expansion card) as you describe it. 4Mb on just the system planar is very hard to realize. Did you also have an expansion card to run the 40Mb HDD? The proprietary stock drives in those units were 20 and 30Mb, nothing larger.

IBMMuseum
March 23rd, 2010, 11:12 AM
Now is there any chance of getting one of these?

For the the several 25SX units I have, as well as the single Reply 25 and PC Enterprises upgrade units, I am very locked in on keeping them. I do have a number of stock 8086-based color Model 25s, but those aren't the level you are looking for (386SX or above). However, we could do a deal on an IBM EduQuest Thirty (IBM 386SLC-25, IDE interface for hard drive and CD-ROM, 72-pin SIMM RAM), being just a slightly larger all-in-one that is a better design than the Model 25.

Anonymous Freak
March 23rd, 2010, 12:18 PM
I'm about 99% certain my 30-286 had all onboard-only RAM. (Various sources do claim that model went up to 4 MB.)

And I'm pretty certain the hard drive was an ISA "HardCard" transferred from a previous 8088 clone; but I may be wrong, and it may have been the stock 30 MB drive. In fact, the more I think about it, the more I'm certain of that. I seem to recall having the 30 MB stock drive running DOS/Windows, and the HardCard running OS/2.

linuxlove
March 23rd, 2010, 02:02 PM
For the the several 25SX units I have, as well as the single Reply 25 and PC Enterprises upgrade units, I am very locked in on keeping them. I do have a number of stock 8086-based color Model 25s, but those aren't the level you are looking for (386SX or above). However, we could do a deal on an IBM EduQuest Thirty (IBM 386SLC-25, IDE interface for hard drive and CD-ROM, 72-pin SIMM RAM), being just a slightly larger all-in-one that is a better design than the Model 25.

I may have to get one of them from ya...

Unknown_K
March 23rd, 2010, 03:13 PM
The Model 30-286 has 4x30 pin SIMM slots, 4MB RAM max (special IBM stuff).

vwestlife
March 23rd, 2010, 06:16 PM
The Model 30-286 has 4x30 pin SIMM slots, 4MB RAM max (special IBM stuff).

There was an official blue-box IBM PS/2 Model 30-286 Memory Upgrade Kit on eBay recently, but it actually only consisted of two 256 kB SIMMs. Apparently the base level 30-286 only came with 512 kB RAM, just like the PC-AT.

Extended memory above 1 MB is of limited usefulness on a 286, anyway. You're better off putting in an ISA RAM card and loading it up with expanded memory, since that's what most classic DOS applications were written to support. Heck, even some DOS games and .MOD players make use of expanded memory if you have it!