IBM 5550

IBM 5550
Company type	Product line
Industry	Personal computers
Founded	March 1983; 43 years ago
Headquarters	Japan
Products	Personal computers with integrated word processing and terminal functions

IBM 5550 represents a line of personal computers introduced by IBM during the 1980s and 1990s, targeting business users across Japan, Korea, Taiwan, and China. Debuting in Japan in 1983 under the name "," this system integrated three distinct functionalities into a single device: a personal computer, a dedicated word processing unit (a separate category in Japan at the time), and an IBM-host connected terminal.

General

The initial IBM PC, released in 1981 and powered by an Intel 8088 CPU, was limited by insufficient processing capabilities and low display resolution, making it inadequate for handling complex East Asian scripts such as Japanese, Korean, and Chinese.

To overcome these challenges, IBM launched the 5550 in March 1983, equipped with an Intel 8086 processor. Originally built on proprietary hardware architecture, the model transitioned in 1987 to IBM's Personal System/2 platform utilizing Micro Channel Architecture, subsequently being renamed the Personal System/55.

After its debut in Japan, IBM expanded the series to incorporate versions supporting Korean, Traditional Chinese, and Simplified Chinese languages. In Japan, promotional campaigns featured actor Kiyoshi Atsumi. Additionally, IBM released the IBM JX aimed at home users in Japan, Australia, and New Zealand, alongside the introduction of DOS/V, which catered to both corporate and consumer segments.

Features

The 5550 was engineered as an integrated terminal designed to merge word processing with personal computing specifically for the Japanese market. To accommodate the widely used 24-dot Mincho style kanji font prevalent in Japanese word processors, it boasted a high-definition graphic display with a resolution of 1024×768 pixels. The first models supported multiple language fonts—including Chinese and Korean—by loading character sets from external storage media.

The system fulfilled three primary roles:

Business-oriented Japanese Personal Computer.
Dedicated Japanese word processor.
Online terminal compatible with IBM host systems.

Initially, the Bunsho Program and emulators operated from floppy disks formatted with a proprietary scheme incompatible with Nihongo DOS. This required users to swap disks or partitions and convert data between applications manually. Subsequent releases integrated these capabilities within Nihongo DOS itself. Eventually, the original emulators and Bunsho Program were superseded by Nihongo 3270 PC (1983), Nihongo 5250 PC (1984), and DOS Bunsho Program (1986).

Early iterations of the 5550 included up to three 5¼-inch '2DD' floppy drives (720 KB each) to separately manage program files, fonts, and user data. Later models adopted font ROM cards for storing character sets, aligning with trends among other Japanese PCs during that decade.

Development

In March 1981, personnel from IBM’s Fujisawa Development Laboratory introduced the concept of a Multi-functional Workstation that would combine word processing capabilities with personal computing. This initiative was overseen by an Independent Business Unit (IBU).

The development team planned for a unified hardware platform supporting both functionalities over a three-to-five-year horizon. Early efforts to merge IBM's Displaywriter System 6580 architecture with that of the IBM PC encountered significant difficulties.

After assessing cost-effectiveness and architectural compatibility, the group chose the Intel 8086 processor rather than the IBM PC's original 8088 CPU to provide enhanced performance suitable for high-resolution displays.

To excel in Japanese word processing tasks, the 5550 utilized a 24-pixel font rendering characters within a 26×29 pixel grid box, achieving an overall display resolution of 1066×725 pixels (equivalent to 41×25 text columns). An alternative option employed a 16-pixel font fitting characters into an 18×21 pixel box at a resolution of 738×525 pixels. Notably, this configuration allowed one additional text column compared to typical Japanese PCs at that time, facilitating superior line breaking.

For personal computing needs, Microsoft developed Nihongo DOS K2.00—a localized version of MS-DOS 2.0 for Japanese users—bundled with a BASIC interpreter specifically adapted for the 5550 platform. The software package also included various programming languages and a Japanese edition of Multiplan.

Although online communication features were not part of the original design plan, terminal functions were incorporated in January 1982 after recognizing their growing significance; this addition extended development timelines.

IBM Japan showcased this project publicly in autumn 1982 following its prior exhibition of only the IBM PC at that year’s Business Show.

Since IBM Japan lacked internal mass production facilities for PCs at that time, manufacturing was outsourced: system units, hard drives, and monitors were produced by Matsushita Electric Industrial, printers by Oki Electric Industry, and keyboards by Alps Electric.

Models

5551-A/B/C/D/E/G/H/J/K/M/P (Fundamental versions positioned adjacent to the display; later iterations were reduced in size, such as the 5540)
5541-B/E/J/K/M/P (Compact variants with display placement; subsequently further minimized)
5561-G/H/J/K/M/P (Larger configurations, all incorporating the Intel 80286 processor)
5530-G/H (Independent units lacking communication adapters; utilized 3½-inch floppy disks)
5535-M (Portable laptop model employing 3½-inch floppy disk drives)

Competition

Within the Japanese market, the Multistation 5550 faced competition from:

Fujitsu FACOM 9450 and FMR product lines
NEC PC-9801 along with the N5200/5300 series

Reception

In 1983, BYTE characterized the 5550 as "a true workstation," positioning it above typical personal computers and comparable to the IBM System/36 minicomputer. The review emphasized its distinctive support for kanji characters combined with sophisticated word-processing capabilities, noting an expanding software vendor network in Japan. The publication anticipated a robust software ecosystem for the 5550, akin to that of American PCs.

Primarily aimed at large corporations utilizing IBM mainframe systems, the 5550 achieved notable adoption; for instance, Meiji Life acquired around 500 units in 1983 to replace IBM terminals, valuing rapid host communication and flexible software compatibility.

By 1985, sales had climbed to roughly 70,000 units annually within Japan. According to a 1986 report by Nikkei Personal Computing, the 5550 commanded a 30% share of the corporate PC market, ranking as the leading enterprise personal computer.

External links

Introducing Multistation 5550 (comprehensive model details)