website/content/museum/ibm-ps-2-model-25.md

title, categories, types, origins, years, cpus, params

title	categories	types	origins	years	cpus	params
IBM PS/2 Model 25	Computers	Professional Computer	U.S.A.	1987	Intel 8086	name image company company_name specs tabs forum_thread photos oc_id source PS/2 Model 25 /media/museum/photos/ibm_model25_1s.jpg /companies/ibm IBM label value NAME PS/2 Model 25 label value MANUFACTURER IBM label value TYPE Professional Computer label value ORIGIN U.S.A. label value YEAR august 1987 label value END OF PRODUCTION Unknown label value KEYBOARD Full stroke keyboard, PS/2 type label value CPU Intel 8086 label value SPEED 8 MHz label value CO-PROCESSOR optional Intel 8087 (math co-processor) label value RAM 512 KB, upgradable to 640 KB label value VRAM Unknown label value ROM Unknown label value TEXT MODES Unknown label value GRAPHIC MODES MCGA graphics : 640 x 480 in monochrome, 320 x 200 in 256 colours label value COLORS 262 144 colours palette label value SOUND Internal PC buzzer label value SIZE / WEIGHT Unknown label value I/O PORTS Parallel port, 9pin serial port, 2 x ps/2 ports, 2 x internal expansion slots (8-bit) label value BUILT IN MEDIA one or two 3.5'' floppy drives (720 KB each) label value OS OS/2, DOS label value POWER SUPPLY Built-in power supply label value PRICE Unknown photos 1151 title subtitle text image MODEL 25 /media/museum/photos/ibm_model25_1.jpg title subtitle text image REAR Thanks to Brandon for this picture /media/museum/photos/ibm_ps2-m25_rear.jpg title subtitle text image MOTHER BOARD Thanks to Brandon for this picture /media/museum/photos/ibm_ps2_m25_mobo.jpg title subtitle text image PS/2 RUNNING WINDOWS 3.0 Windows 3.0 running in high resolution with 16 shades of grey due to a VGA card installed. Thanks to Brandon for this picture /media/museum/photos/ibm_ps2_windows3_ss.jpg 1183 url date https://web.archive.org/web/20230608093550/http://www.old-computers.com/museum/computer.asp?c=1183 2023-06-08

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.