On This Day - 5th March

Sinclair Research launched the ZX81 in Britain on 5 March 1981, replacing the ZX80 and substantially reducing the cost of entry into home computing.

The ZX81 was offered for £49.95 in kit form or £69.95 ready-built. It featured 1K of RAM and an 8K ROM containing Sinclair's improved BASIC, while a Ferranti-designed ULA reduced the computer's electronics to just four main chips.

The machine was designed as a simpler and cheaper successor to the ZX80. It was manufactured in Dundee by Timex and, as sales expanded, became available through high-street retailers including W.H. Smith.

The ZX81 went on to become one of Britain's most influential early home computers, introducing large numbers of people to programming and helping establish the market that would soon develop around the ZX Spectrum.

Image: Sinclair ZX81 — Journey234. Public Domain.

The 6th ZX Microfair was held on Saturday 5 March 1983 at the New Horticultural Hall, Victoria, London. Home Computing Weekly described it as Mike Johnston's most successful Microfair to date, with nearly 8,000 visitors attending.

Queues stretched along the street, reportedly four people deep, and nearly 100 exhibitors took space at the show. The Microfair had grown considerably since the first event in September 1981 and had become an important meeting place for Sinclair computer users, software developers and hardware suppliers.

The show featured a large number of new products for the ZX81, ZX Spectrum and Jupiter Ace. dK'Tronics demonstrated a new light pen for the Spectrum, while Kempston Micro Electronics showed a new Centronics interface for the Spectrum. Cobra Technology demonstrated its communications package for the ZX81, including access to British Telecom Gold.

New keyboards were also prominent. Kayde Electronic Systems showed a wooden mock-up of its £45 keyboard for the ZX81 and Spectrum, while Memotech's new ZX81 keyboard was available in three colours. AGF Hardware demonstrated its Joystick Interface Module 2 for the Spectrum, ZX81 and Jupiter Ace.

A number of serious and educational programs were on display alongside games. University Software exhibited programs covering matrix operations, polynomials, integration, regression and linear programming. Jaysoft showed Compufile, intended for use as an address book, diary and catalogue, together with the Personal Accounting Utilities Ledger (PAUL), a household budgeting program. Campbell Systems launched Masterfile-16, a machine-code version of its database program for the 16K Spectrum.

Other notable software included Microsphere's Evolution, a simulation of evolution on the Spectrum, and new business and educational software such as Hilton Computer Services' Personal Banking System and Bank Reconciliation program. A high-resolution graphics board for the ZX81, providing programmable 256 × 192 graphics using its own 2K EPROM, was demonstrated by Digital Integration.

The show also featured numerous new games and entertainment programs, including Dragon's Lair, Joust, Labyrinth, Mad Martha, Space Zombies, Cosmic Raider, Triad, Everest Ascent, Volcanic Dungeon and Superchess II. The major software houses, including Quicksilva and Abbex, were also represented.

The scale and variety of products at the 6th ZX Microfair provide a useful contemporary snapshot of the Sinclair market in early 1983, shortly before the Spectrum became established as one of Britain's dominant home computers.