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I > IBM  > PS/2 Model 25     


IBM
PS/2 Model 25

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.
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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
rob (usa)

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
rob (usa)

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
rob (usa)

 

NAME  PS/2 Model 25
MANUFACTURER  IBM
TYPE  Professional Computer
ORIGIN  U.S.A.
YEAR  august 1987
END OF PRODUCTION  Unknown
KEYBOARD  Full stroke keyboard, PS/2 type
CPU  Intel 8086
SPEED  8 MHz
CO-PROCESSOR  optional Intel 8087 (math co-processor)
RAM  512 KB, upgradable to 640 KB
VRAM  Unknown
ROM  Unknown
TEXT MODES  Unknown
GRAPHIC MODES  MCGA graphics : 640 x 480 in monochrome, 320 x 200 in 256 colours
COLOrsc  262 144 colours palette
SOUND  Internal PC buzzer
SIZE / WEIGHT  Unknown
I/O PORTS  Parallel port, 9pin serial port, 2 x ps/2 ports, 2 x internal expansion slots (8-bit)
BUILT IN MEDIA  one or two 3.5'' floppy drives (720 KB each)
OS  OS/2, DOS
POWER SUPPLY  Built-in power supply
PRICE  Unknown





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