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Sinclair ZX81 Personal Computer -
the heart of a system that grows with you.

Sinclair Research, 1981

1980 saw a genuine breakthrough - the Sinclair ZX80, the world's first complete personal computer for under £100. Not surprisingly, over 50,000 were sold.

In March 1981, the Sinclair lead increased dramatically. For just £69.95 the Sinclair ZX81 offers even more advanced facilities at an even lower price. Initially, even we were surprised by the demand - over 50,000 in the first 3 months!

Today, the Sinclair ZX81 is the heart of a computer system. You can add 16 times more memory with the ZX RAM pack. The ZX Printer offers an unbeatable combination of performance and price. And the ZX Software library is growing every day.

Lower price: higher capability

With the ZX81, it's still very simple to teach yourself computing, but the ZX81 packs even greater working capability than the ZX80.

It uses the same micro-processor, but incorporates a new, more powerful 8K BASIC ROM - the 'trained intelligence' of the computer. This chip works in decimals, handles logs and trig, allows you to plot graphs, and builds up animated displays.

And the ZX81 incorporates other operation refinements - the facility to load and save named programs on cassette, for example, and to drive the new ZX Printer.

Higher specification, lower price - how's it done?

Quite simply, by design. The ZX80 reduced the chips in a working computer from 40 or so, to 21. The ZX81 reduces the 21 to 4!

The secret lies in a totally new master chip. Designed by Sinclair and custom-built in Britain, this unique chip replaces 18 chips from the ZX80!

New, improved specification

  • Z80A micro-processor - new faster version of the famous Z80 chip, widely recognised as the best ever made.
  • Unique 'one-touch' key word entry: the ZX81 eliminates a great deal of tiresome typing. Key words (RUN, LIST, PRINT, etc.) have their own single-key entry.
  • Unique syntax-check and report codes identify programming errors immediately.
  • Full range of mathematical and scientific functions accurate to eight decimal places.
  • Graph-drawing and animated display facilities.
  • Multi-dimensional string and numerical arrays.
  • Up to 26 FOR/NEXT loops.
  • Randomise function - useful for games as well as serious applications.
  • Cassette LOAD and SAVE with named programs.
  • 1K-byte RAM expandable to 16K bytes with Sinclair RAM pack.
  • Able to drive the new Sinclair printer.
  • Advanced 4-chip design: microprocessor, ROM, RAM, plus master chip - unique, custom-built chip replacing 18 ZX80 chips.

Kit or built - it's up to you!

You'll be surprised how easy the ZX81 kit is to build: just four chips to assemble (plus, of course the other discrete components) - a few hours' work with a fine-tipped soldering iron. And you may already have a suitable mains adaptor - 600 mA at 9 V DC nominal unregulated (supplied with built version).

Kit and built versions come complete with all leads to connect to your TV (colour or black and white) and cassette recorder.

16K-byte RAM pack for massive add-on memory.

Designed as a complete module to fit your Sinclair ZX80 or ZX81, the RAM pack simply plugs into the existing expansion port at the rear of the computer to multiply your data/program storage by 16!

Use it for long and complex programs or as a personal database. Yet it costs as little as half the price of competitive additional memory. With the RAM pack, you can also run some of the more sophisticated ZX Software - the Business & Household management systems for example.

Available now - the ZX Printer for only £49.95

Designed exclusively for use with the ZX81 (and ZX80 with 8K BASIC ROM), the printer offers full alphanumerics and highly sophisticated graphics.

A special feature is COPY, which prints out exactly what is on the whole TV screen without the need for further intructions. At last you can have a hard copy of your program listings-particularly useful when writing or editing programs.

And of course you can print out your results for permanent records or sending to a friend.

Printing speed is 50 characters per second, with 32 characters per line and 9 lines per vertical inch.

The ZX Printer connects to the rear of your computer - using a stackable connector so you can plug in a RAM pack as well. A roll of paper (65 ft long x 4 in wide) is supplied, along with full instructions.

How to order your ZX81

BY PHONE - Access, Barclaycard or Trustcard holders can call 01-200 0200 for personal attention 24 hours a day, every day.

BY FREEPOST - use the no-stamp needed coupon below. You can pay by cheque, postal order, Access, Barclaycard orTrustcard.

EITHER WAY - please allow up to 28 days for delivery. And there's a 14-day money-back option. We want you to be satisfied beyond doubt and we have no doubt that you will be.

To: Sinclair Research, FREEPOST, Camberley, Surrey, GU15 3BR


Item Code Item price
Sinclair ZX81 Personal Computer kit(s). Price includes ZX81 BASIC manual, excludes mains adaptor. 12 49.95
Ready-assembled Sinclair ZX81 Personal Computer(s). Price includes ZX81 BASIC manual and mains adaptor. 11 69.95
Mains Adaptor(s) (600 mA at 9 V DC nominal unregulated). 10 8.95
16K-BYTE RAM pack. 18 49.95
Sinclair ZX Printer. 27 49.95
8K BASIC ROM to fit ZX80. 17 19.95
Post and Packing.   2.95