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.
The PS/55 is the successor to IBM 5550 (Multistation 5550), but its architecture is based upon IBM PS/2. The first line-up of the series consisted of rebranded 5550 models except the Model 5570-S which was based on the PS/2 Model 80 (IBM 8580). Unlike the PS/2, most PS/55-based models have a 32-bit (80386 or 80486) CPU and Micro Channel (MCA) bus for the high-end business computing market. IBM Japan was hesitating to sell personal computers for consumers because the IBM JX failed.[2] The AT bus model was released for home users in 1991.
Model 5550-T Booting-up
Features
Display Adapter
Display Adapter II
The MCA video card called Display Adapter has a Japanese font containing nearly 7,000 glyphs stored in its ROM, which enables PS/2-based computers to display Japanese text without loading the font into memory. Similar to the IBM 5550, the display resolution in character mode is 1040×725 pixels (12×24 and 24×24 pixel Mincho font, 80×25 text) in 8 colors. The graphics mode is 1024×768 pixels in 16 colors. This is the same resolution as 8514/A and XGA/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, 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 it passes the video signal from the motherboard to adapter's VGA 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 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 later machines cannot run the special Japanese DOS, instead requiring the use of DOS/V with software-rendered kanji.
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 method.
5576-001 - Same layout as 5550 type 1 (5556-001) keyboard.
^"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. 19 November 2008. Retrieved June 7, 2016.
^戸塚, 正康 (1991). "PS/2とPS/55が誕生". 日本IBMのパソコン新戦略 (in Japanese). 日本工業新聞社. pp. 111–113. ISBN4-8191-0856-5.
^"特集 最新機種レポート'88 : PS/2互換の日本語マシン 日本アイ・ビー・エム IBM パーソナルシステム/55 モデル5550-S/T モデル5570-T". ASCII (in Japanese). ASCII Corporation. 12 (7): 158–163. 1988. ISSN0386-5428.
