Personal System/55

PS/55 Model 5550-T
Also known as	パーソナルシステム/55
Developer	IBM
Manufacturer	IBM Fujisawa (PS/2 line), Matsushita Electric Industrial (5550 line)
Type	Professional Computer
Release date	1987; 38 years ago (1987)
Discontinued	2001[1]
Operating system	Japanese DOS (K3.3 - J5.0) PC DOS (3.3 -) DOS/V OS/2 Windows 3.x
Predecessor	IBM 5550 IBM JX

ThePersonal System/55 (パーソナルシステム/55) orPS/55 is apersonal computer series released fromIBM Japan in 1987.

The PS/55 is the successor toIBM 5550 (Multistation 5550), but its architecture is based uponIBM PS/2. The first line-up of the series consisted of rebranded 5550 models except the Model 5570-S which was based on thePS/2 Model 80 (IBM 8580). Unlike the PS/2, most PS/55-based models have a 32-bit (80386 or80486) CPU andMicro Channel (MCA) bus for the high-end business computing market. IBM Japan was hesitating to sell personal computers for consumers because theIBM JX failed.^[2] TheAT bus model was released for home users in 1991.

The MCA video card calledDisplay Adapter has a Japanese font containing nearly 7,000glyphs stored in itsROM, which enables PS/2-based computers to displayJapanese text without loading the font into memory. Similar to the IBM 5550, the display resolution in character mode is 1040×725pixels (12×24 and 24×24 pixelMincho font, 80×25 text) in 8 colors. The graphics mode is 1024×768 pixels in 16 colors. This is the same resolution as8514/A andXGA/A, but not compatible.

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 applications. Since the model 5550-S released in 1988, theDisplay Adapter II that improved the PS/2 compatibility was introduced. In theboot sequence, the Display Adapter enablesVGA on the motherboard, and it passes the video signal from the motherboard to adapter'sVGA 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). The adapter has 1 MB of video RAM, and 256 KB of RAM for user-defined characters.^[3]

Most PS/2-based models have compatibility with the Display Adapter II. VGA and the following display modes are supported:

• 1040×725 pixels with 80×25 characters in 8 colors ormonochrome
• 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 later machines cannot run the special Japanese DOS, instead requiring the use ofDOS/V with software-rendered kanji.

The following keyboards have thePS/2 port. These keyboards have newscancode sets (81h, 82h, 8Ah) to support additional keys for Japaneseinput method.

• 5576-001 - Same layout as 5550 type 1 (5556-001) keyboard.
• 5576-002 - Japanese layout based on101 Enhanced keyboard, but usesAlps Electric Co.mechanical key switches.
• 5576-003 - Space-saving version of 5576-002
• 5576-A01 -OADG reference keyboard.^[4]
• 5576-A01 -OADG reference keyboard.^[5]

• Tower
  • 5570-S, T, V (Early tower model. 5570-S, the first model of PS/55, doesn't support English versions of PC DOS and OS/2^[6])
  • 5580-Y, W (Late tower model)
• Business Desktop (Predecessor toIBM 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 toPS/V Vision)
  • 5510-Z, S, T (VGA model. Predecessor toPS/V)
• Laptop
  • 5545-T (Integratedplasma display)
  • 5535-S (the first model pre-installedDOS/V)^[7]
• A4 Notebook
  • PS/55 Note (Predecessor toThinkPad. AT bus or MCA bus.)
• RebrandedIBM 5550
  • Model G to P (1987-1991)

• NEC PC-98,N5200/N5300 [jp]
• Fujitsu FMR
• Toshiba J-3100
• AX architecture

Wikimedia Commons has media related toIBM PS/55.

• DOS/V

• 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.

• PS/55, Japanese PS/2 Retrieved September 28, 2022

• X86 IBM personal computers
• Computer-related introductions in 1987
• IBM PS/2

• CS1 Japanese-language sources (ja)
• Webarchive template wayback links
• Articles with short description
• Short description is different from Wikidata
• Articles containing Japanese-language text
• Commons category link is on Wikidata