IBM Personal System/55

The Personal System/55 (パーソナルシステム/55) or PS/55 is a personal computer series released from IBM Japan in 1987.

PS/55 Model 5550-T
DeveloperIBM Japan
TypeProfessional Computer
Release date1987 (1987)
Discontinued2001[1]
Operating systemJapanese DOS (K3.3 - J5.0)
PC DOS (3.3 -)
DOS/V
OS/2
Windows 3.x
PredecessorIBM 5550
IBM JX

The PS/55 is the successor to IBM 5550 (Multistation 5550), but its architecture is based upon IBM PS/2, perhaps it is also an IBM clone. Most models have Micro Channel (MCA) for business use. Later, the AT bus model was released for home users.

Features

Display Adapter
Display Adapter II
Screenshot of MIFES (text editor) in character mode

Similar to IBM 5550, the character mode is 1040×725 pixels (12×24 and 24×24 pixel Mincho font, 80×25 characters) in 8 colors. It can display Japanese characters read from a font ROM on the video card. The graphics mode is 1024×768 pixels in 16 colors. This is the same resolution as 8514/A and XGA/A, but not compatible. These modes are implemented in an MCA video card called Display Adapter, and installed in the system unit.

The first Display Adapter was installed in the model 5570-S, also known as the first Micro Channel machine of PS/55. It had a compatibility problem with PS/2 softwares. Since the model 5550-S released in 1988, the Display Adapter II that improved the PS/2 compatibility was introduced. In the boot sequence, the Display Adapter enables VGA on the motherboard, and the video signal is output for the Display Adapter through an MCA connector. When using Japanese DOS, VGA is disabled, and the Display Adapter switches its video selector from VGA to own video chip. In addition, it added the 256 color mode (1024×768 pixels in 256 colors chosen from 262,144 colors).

Most models have compatibility with the Display Adapter II. VGA and the following display modes are supported:

  • 1040×725 pixels with 80x25 characters in 8 colors or monochrome
  • 1024×768 pixels graphics in 16 colors or monochrome
  • 1024×768 pixels graphics in 256 of 262,144 colors

Later, XGA and VGA-only models were released. These machines cannot run the Japanese DOS. Instead it required DOS/V.

JIS layout keyboard
5576-002 Keyboard

The following keyboards have the PS/2 port. These keyboards have new scancode sets (81h, 82h, 8Ah) to support additional keys for Japanese input.

Models
Internal view of Model 5550-T
  • Tower
    • 5570-S/T/V (Early tower model. 5570-S, the first model of PS/55, doesn't support English version of PC DOS and OS/2 because it isn't 100% compatible with PS/2.[3])
    • 5580-Y/W (Late tower model)
  • Business Desktop (Predecessor to IBM PC 300/700 series)
    • 5560-W/N （Hi-end desktop）
    • 5550-S/T/V/W/N/Y/L/R （Mainstream desktop）
    • 5540-T （Low-end desktop）
  • For small business, home users
    • 5530-Z/S/T/U/W (Desktop with integrated a display, Predecessor to PS/V Vision)
    • 5510-Z/S/T (VGA model. Predecessor to PS/V)
  • Laptop
  • A4 Notebook
    • PS/55note (Predecessor to ThinkPad. AT bus or MCA bus.)
  • Rebranded IBM 5550
    • Model G~P (1987-1991)

Competitors

See also

References
  1. "マルチステーション、ＰＳ／Ｖ、ＰＳ／２、ＰＳ／５５の一部保守活動中止の発表" [Some model of Multistation, PS/V, PS/2, PS/55 End of Life Announcement] (in Japanese). IBM Japan. Retrieved June 7, 2016.
  2. "IBM 20万円を切った低価格DOS／V専用パソコン登場"(May 7, 1991), Retrieved June 2, 2016
  3. 'ASCII EXPRESS：日本IBMがIBM PS/2互換の80386マシン3機種を発表 英語版OS/2用アプリケーションもすべて動作可能に'.ASCII June 1988, Ascii

Further reading
  • IBM Japan (1990). IBM PS/55ハードウェア モデル5550-S/T/V技術解説書 [IBM PS/55 Hardware:Model 5550-S/T/V Technical Reference]. Ohmsha. ISBN 4274076245.
Preceded by
IBM 5550		 IBM PS/55
1987 - 2001		 Succeeded by
IBM PS/V
Preceded by
IBM JX		 Succeeded by
IBM PC Series
Succeeded by
IBM ThinkPad
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