Welcome to this new support forum for all 16KZX81/TS1000 enthusiasts everywhere!

"The Sinclair ZX81 Support Page" was maintained by Steven McDonald but is sadly no longer updated (very much)!

I provide an archive here for reference purposes only! (I don't have the time anymore... Sorry!)

Last Update: Saturday, 31st Dec, 2011.

"Whatever else you do, keep using the computer. If you have a question 'What does it do if I
tell it such & such?' then the answer is easy: type it in & see. Whenever the manual tells
you to type something in, always ask yourself 'What could I type instead?' & try out your
replies. The more of your own stuff you write, the better you will understand the ZX81.
(This is called unprogrammed learning.) Regardless of what you type in, you cannot damage
the computer."

From ZX81 BASIC Programming, Second Edition
By Steven Vickers
(c) Sinclair Research Limited, 1980

INTRODUCTION TO THIS SITE! - WHAT IS A ZX81?

In case you are reading this and thinking to yourself, "what on earth is a ZX81", either because you never heard of it or were not born at the time, then read on...

Another question often asked is, "why the fascination with that old computer?". Well let me try and explain...

The ZX81 was the successor to the ZX80 and one of the cheapest home computers. Sinclair was able to make huge manufacturing savings by the inclusion of a custom Ferranti ULA or "glue chip" that connected the other components together in a way that made them do more than they otherwise would.

This ULA was responsible for the ZX81's low chip count. Other things like the cheap membrane keyboard used also kept costs down. In the UK, it was the first sub £100.00 computer - cheaper than its predecessor and more powerful to boot!

The chips consisted of a Z80 A CPU (clocked at 3.5Mhz), an 8KBASIC ROM, 1KB RAM and the ULA. There was no graphic chip; the CPU had to do the job! This was actually a major plus point for clever programmers, as it gave them total control over how the TV display was generated. Sir Clive himself once said that High Res was impossible...

I often wonder if he ever knew about what was achieved with his machine in later years?

The ZX81 was sold retail and as a DIY kit back in 1981 and thousands of them were sold at the time. A 16K memory expansion pack that connected directly onto the expansion bus (prone to wobble) was available that boosted its capacity for serious applications.

Programs were stored on tape through the cassette interface operating at a slightly slow 300Baud and a special thermal ZX printer was also available.

Clever software was later written to LOAD and SAVE from tape at vastly increased speeds and to print out on the ZX Printer in High Res.

Over the years many hardware experts have come up with interesting add-on projects for the ZX81. Back in the 80's, I kept in contact with a great guy and clever programmer, (Fred Nachbaur) who actually had a disk drive interface for his ZX81! Devices such as High Res colour graphics boards, sound cards, SCRAM memory boards, replacement keyboards etc. were available from enterprising companies.

People such as Wilf Rigter, Kevin Baker, Kai Fischer, Peter Liebert-Adelt and The German ZX-Team are still very much active!!! In addition, here at the end of the 90's, many ZX81 enthusiasts are using the Internet to stay in touch, help each other out and to share their ideas and projects. Indeed, Wilf Rigter continues to develop designs for a portable ZX81 for the 90's complete with LCD screen etc.

So what is it about this machine then?

Well, it was a lot of people's first computer and had an excellent manual that introduced you to its BASIC programming language. After that you could progress to programming the machine in Z80 assembler, if you fancied, that gave you full control over the machine at every level!

I think that it is this power over the machine and the ZX81'sinherently simple but extremely clever design that made it so attractive.

Although technically, its successor, the ZX Spectrum was far more advanced, featuring colour displays and sound, to me it just wasn't as exciting a machine because you couldn't take direct control of the tv picture generation for example!

These are the things that make this machine stand out from the rest and to this day you can still buy ZX81 kits on the Net and build for yourself this most rewarding little computer.

The ZX81 is an excellent machine to learn about the basics of computers on and the principles learnt can still be applied to current computing in the90's!

Above all, the ZX81 was a computer you could experiment with and try things out on! The paragraph from the ZX81 manual quoted at the start of this page is my favourite from any computer manual I have ever read, as it encourages you to not take things for granted and to figure things out for yourself. When I was starting out on computers, this was a great philosophy to follow and today I would say that everything I know about them goes back to this excellent advice from Steven Vickers in that book!

So even if you have an all-singing, all-dancing Pentium II300Mhz multimedia computer, you could still learn a thing or two from the old SinclairZX81! So why not try out some of the emulators or programs available here.

There are a few PC ZX81 emulators out there but none come even close to matching the realism of Carlo Delhez's excellent XTender2 - now in Beta testing.

If you still own a ZX81, get it down from the attic and dust it off and be prepared to be surprised at what can still be achieved with it!

Computer: ZX81
Manufacturer: Sinclair Research Ltd.
Released: 1981
CPU/Clock speed: Z80A clocked at 3.5 MHz
ROM: 8 Kbyte (BASIC AND OS)
RAM (Expandable): 1 (16) Kbyte
Screen: TV (50 or 60Hz)
Text mode: 32*24
Graphics mode: 64*44
Colors: Black/White
Sound: None
Keyboard: Membrane Keyboard (40 keys)
Interfaces: TV, Earphone, Microphone, Expansion Bus
Size (in mm): 167*175*40

LATEST ZX81 NEWS AND DEVELOPMENTS:

13th Nov, 2001.

Greetings fellow enthusiasts! The page is back up on yet another new server! Thanks to www.savemypc.com for sponsoring this page!

Please bear with me at the moment - there is much to be fixed on this page!!

In the meantime, I will say that if you need to contact me - send an email to stevenmcd@msn.com and nowhere else! It will reach me.

I felt it was more important to get this page back up than to fix everything that's wrong in one go.

The surf.to address is not updated yet. The ZX81 survey link should not be used. Some links are broken.

Bear with me - I will get there!

So what's new?

Well... I can now present the first update to this site in around two years!

Click below for the exclusive new Software Farm Tribute Page - complete with downloads - I haven't seen 'Spectrumiser' or 'Booster' featured anywhere else!

Visit the Software Farm Tribute Page

14th Feb, 1999.

Fred's been busy lately, converting over more of his files. Take a look below at this rather large update! Thanks, Fred!