IBM was struggling in 1986 against Apple's Macintosh series, so IBM set out to create something that would defeat the Macintosh. IBM came up with a all-in-one similar to the Macintosh. However, the Model 25 & 30 were the low-end (budget) models of the PS/2 range.
The PS/2 Model 25 became quite popular with businesses, but never made it strong with the home market.
The PS/2 Model 25 & 30 were the only system using the MCGA (Multicolor Graphics Adapter) standard. They came with this video features built-in. MCGA offered all text and graphic modes of the CGA standard plus 640x480 monochrome and 320x200, 256 colors (out of a palette of 262,144). It announced the future VGA standard which will become much more popular.
Model 25 & 30 were also the only PS/2 systems using an 8-bit ISA bus (like PC ATs), as opposed to other PS/2 models which used a 16 or 32 bit MCA bus.
Thanks to Alex Rushing for info and picture
Further information from Brandon:
The model 25 came in two models, a monochrome model, and a color model. The monochrome model usually is called "Type 001", the color one being "Type 004".. There never was a type 002, or 003.
The motherboard for the color and black and white models are exactly the same, minus some revisions on the later years. They were always surface mounted though (most of the chips anyway).
They are a tough machine, though when you install one in a new room, it NEEDS to let sit in the room for a couple hours, otherwise the power supply/motherboard will die.
While the floppy drives were 720KB, they "could" use 1.44MB drives, as long as the interface was the same.
They contain TWO BIOS's in them. One called the CBIOS, and the other called the ABIOS.. CBIOS is "Compatible BIOS", and is used for DOS or Windows 3.0 and under... ABIOS, or "Advanced BIOS", is used when it runs OS/2.. OS/2 is the native OS to this unit. They also had an option for a hard drive.
We need more info about this computer ! If you designed, used, or have more info about this system,
please send us pictures or anything you might find useful.
I have a model 25 that loads Basic at the end of it''s boot-up and I can not figure out how to close Basic and get to a DOS prompt. The unit has a hard-drive and a 3.5 floppy (720 or 1.44?) . Has anyone dealt with this issues?
Friday 5th June 2015
The model 25 also came in a 286 version with IDE AND there was ALSO a Model 25SX that came with a 386 processor, VGA and IDE. I have both the Model 25sx with 12 meg memory and 8 gig storage on compact flash with sound card and the Model 25 286 with a sound card and hard drive. Both of these are in the all in one design shown above and the 386 sx version is thought of to be very rare.
Saturday 27th December 2014
i recently saved one of these from the trash its a model 55sx but sadly the dallas clock battery is dead causing it to lose its cmos settings which requires a reference disk to fix i removed the old clock battery untill i could get a replacement but the computer shows no image on the screen with out it installed and i can no longer find the old one
Sunday 5th October 2014
PS/2 Model 25
END OF PRODUCTION
Full stroke keyboard, PS/2 type
optional Intel 8087 (math co-processor)
512 KB, upgradable to 640 KB
MCGA graphics : 640 x 480 in monochrome, 320 x 200 in 256 colours
262 144 colours palette
Internal PC buzzer
SIZE / WEIGHT
Parallel port, 9pin serial port, 2 x ps/2 ports, 2 x internal expansion slots (8-bit)