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IBM JX

From Alfawiki
IBM JX
Company typePersonal computer
IndustryComputer hardware
PredecessorIBM PCjr
Founded1984
FounderIBM Japan
Defunct1987
Headquarters
Japan
Area served
Japan, Australia, New Zealand
ProductsPersonal computer (IBM 5511)

The IBM JX (also known as the JXPC) was a personal computer introduced in 1984, targeting the markets of Japan, Australia, and New Zealand. Developed by IBM Japan and manufactured by Matsushita Electric Industrial, it was built upon the IBM PCjr platform and identified as the IBM 5511. Unlike general consumer models, this system was aimed primarily at the Australasian public education sector. It came in three memory variants: JX with 64 KiB, JX2 with 128 KiB, and JX3 with 256 KiB, offering expandability up to 512 KiB. Significantly, the JX marked IBM’s first use of 3.5" floppy disk drives in a PC.

IBM Japan initially forecasted sales reaching 200,000 units but ultimately produced only around 40,000 before discontinuing the product line in 1987. To commemorate its 50th anniversary, IBM Japan distributed approximately 15,000 units among its employees.

General

The IBM JX set itself apart from the PCjr mainly by replacing the PCjr's much-criticized chiclet keyboard with a more professional one. It featured dual 3.5" floppy drives as standard, with optional additions of a 5.25" floppy or hard disk drives positioned on top of the main chassis. Unlike the PCjr, the JX did not support "sidecar" expansion modules and lacked a DMA controller. It incorporated a distinct Enhanced Color Graphics Adapter (ECGA), capable of displaying 16 colors simultaneously at a resolution of 320×200 pixels, while maintaining the PCjr’s four-channel sound hardware—though only a limited number of software titles, such as those from Sierra On-line, utilized these capabilities.

Configuration

The PCjx included several notable features:

  • One or two 3.5" floppy disk drives with initial capacity of 360 KB later upgraded to 720 KB
  • Infrared wireless keyboard
  • Video output supporting sixteen colors
  • Stackable expansion modules
  • Joystick ports
  • Cartridge slots

In Japan, the PCjx was offered in white and dark gray color options; outside Japan, only dark gray versions were available—an uncommon choice compared to IBM’s usual beige palette. Japanese models incorporated a Japanese font stored on a 128 KB ROM chip that supported text display in a default mode of 40×11 characters. With an Extended Display Cartridge installed, it could provide a 40×25 Japanese text mode at 720×512 pixel resolution, similar to that found in the IBM 5550, along with a compatible BASIC interpreter.

A significant drawback was its incompatibility with standard ISA bus expansion cards used in IBM PCs.

The operating system suite included PC DOS 2.11 alongside Microsoft Disk BASIC and Microsoft Advanced BASIC. When booted without a floppy disk inserted, the system would load Microsoft Cassette BASIC compatible with IBM PCjr BASIC. However, due to BIOS limitations designed to emulate a 5.25" drive, PC DOS 2.11 recognized only half of the tracks on a 3.5" disk drive. This restriction was later resolved by a BIOS update coupled with PC DOS 3.21, enabling full access to the 720 KB capacity.

Commonly chosen accessories featured a stackable external 5.25" floppy drive with 360 KB capacity, an external hard disk offering 10 MB storage (also stackable), and joysticks. IBM never introduced a 3270 terminal emulation adapter for the PCjx, directing enterprise users instead to higher-end IBM PC and XT systems.

Reception

In its 1985 review, BYTE characterized the JX as "a Japanese product for the Japanese," highlighting its pricing structure and features tailored specifically for that market segment. Compatibility with PCjr peripherals and inclusion of joystick ports indicated IBM Japan’s intent to appeal to consumers interested in video games—a highly competitive market at the time. However, BYTE anticipated only limited commercial success due to its modest performance relative to competitors.

Although positioned as a home computer solution, sales remained sluggish throughout 1986. Estimates suggest approximately 2,000 units sold within Japan and around 10,000 globally when including direct corporate sales and distributions to employees. Retailers reported weak consumer demand even when offering significant discounts. By comparison, NEC’s PC-88 series achieved sales of about 75,000 units within four months following its November 1985 launch.

Critiques centered on the decision to utilize an Intel 8088 processor rather than adopting more advanced CPUs like the Intel 80286 prevalent in Japan at that time. This choice led enthusiasts to regard the system as outdated and negatively influenced word-of-mouth recommendations among potential buyers. The JX’s design emphasis on compatibility with Western-oriented PCjr software did not align well with Japanese consumer preferences and suffered from limited software availability due to insufficient collaboration between IBM Japan and independent software developers.

Although it represented IBM Japan’s first foray into IBM PC compatible hardware, higher-end models such as the PC/XT and PC/AT were introduced domestically by late 1985.

The IBM 5550 proved successful within corporate environments relying on IBM mainframe integration and offered robust Japanese text support alongside word processing features suited for small business users. In early 1985, IBM Japan launched the IBM 5540 as an entry-level alternative positioned between the higher-end 5550 and the lower-tier JX in terms of price and compatibility—a move that confused customers; some purchasers of the JX expressed regret upon learning about the forthcoming release of this more compatible model.

Development efforts for both the JX and the 5540 consumed considerable resources focused on maintaining backward compatibility. It is reported that both systems were developed concurrently at IBM’s Fujisawa Laboratory under pressure from headquarters to prioritize releasing the JX first.

Masahiko Hatori, responsible for developing the JX BIOS and DOS, recalled internal concerns regarding late market entry despite management’s optimistic outlook. He explained that selecting the slower Intel 8088 processor was part of a strategy intended to keep consumer-class systems like the JX positioned below business-oriented models such as the IBM 5550 in both performance and cost—rendering it less appealing for consumers seeking rapid gaming responsiveness.

IBM Japan never publicly released precise sales data; however, industry estimates indicate production reached roughly 40,000 units by 1987. Plans for a fully PC/AT compatible successor dubbed "JX II," which would have supported Japanese text display, were abandoned in 1986. The company refrained from launching another consumer-focused product until entering educational markets with the PS/55Z in 1988.

External links

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