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1980s Computers Explanation of terms

The IBM PC Junior



International Business Machines (US)


PC Junior

Date Launched

Announced November 1st 1983
Not distributed to customers until March 1984.


Approx. £800 without disk drive.

Microprocessor type

Intel 8088 @ 4.77 MHz

ROM size

24 kilobytes

Standard RAM

64 kilobytes in standard version.
128 kilobytes in 'enhanced' version.

Maximum RAM

Officially 128 kilobytes but 640 KB was possible.

Keyboard type

Original chiclet keyboardOriginally a quite poor 62-key unit with stiff action and short key travel (right). Connected to main box via an infra-red link.
A normal style keyboard as shown in the top picture became available later.

Supplied language

Simple Microsoft BASIC on internal ROM and expanded BASIC on cartridge.
MSDOS 2.1 could be run if optional floppy disk drive fitted.

Text resolution

40 or 80 columns x 25 lines.

Graphics resolution

160 x 200, 320 x 200 or 640 x 200 pixels

Colours available

16 at lowest resolution.


Three channels through internal or external speaker

Cassette load speed

Not known. IBM charged $30 for the cable needed to connect the PC Jr to a cassette recorder!
A 5¼ inch floppy disk drive storing 320 KB was an optional extra for the basic model and a standard item in the enhanced model. In practice the disk drive was almost essential.

Special features

A cheap version of the IBM business PC.
There was very little else about the PC Junior to make it stand out.

Good points

High build quality.
Disk-compatible with the popular IBM PC.

Bad points

Some software written for the business version of the IBM PC would not run on the Junior because of hardware differences (i.e it was not fully 'IBM compatible').
The PC Jr was very expensive compared to other home computers.
Back panel of PC JrThe connectors for external hardware (RS 232, video out, printer, etc.) were almost all non-standard.
It was not possible to connect a hard disk to the PC Jr.
The Junior could not use expansion cards designed for the PC/XT.

How successful?

Sales were low by IBM standards and production ended in March 1985.


The PC Junior was IBM's attempt to enter the home computer market, to complement its success in the business market with the full-size IBM PC. Thus the PC Jr was a cut-down IBM PC but it was cut to the point of being almost unusable. It lacked a 'direct memory access' controller and this prevented much popular software for the IBM PC from running on the Junior. Maybe this was a deliberate policy by IBM to prevent people buying the Junior instead of the much more expensive IBM PCs but in practice it negated one of the few reasons for considering buying the Junior.

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