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The Memotech MTX Series      

About the Memotech MTX Series


Having made their name making add-ons for the Sinclair ZX81, Memotech introduced a range of computers of their own in 1983 - the Memotech MTX series. If you want to know more about the Memotech company and its founders, Geoff Boyd (hardware) and Robert Branton (software), take a look at my History of Memotech page.

Like many of the other computers at the time, including the Sinclair ZX range, Memotech computers were based on the Zilog Z80 8-bit microprocessor. The computers were originally available in two models, the MTX500 with 32KBytes of RAM (275) and the MTX512 with 64KBytes of RAM (315). The MTX500 was launched at the Earls Court Computer Fair in June 1983 and the MTX512 was available later in the year.

The final machine from Memotech Computers, released in September 1984, was the RS128. The RS128 was fitted with 128 KBytes of RAM and used page switching to get around the Z80 restriction of only being able to address a maximum of 64KBytes of RAM. Memotech released a "low cost" CP/M package consisting of a MTX512, 500KB disk drive and an 80-column board that fitted inside the MTX case in August 1985. At 499, this was much cheaper than the FDX option, but came too late to save the Company.

The original company (Memotech Limited) went into receivership in early 1986. Geoff Boyd started up Memotech Computers Limited to market the RS128 and an upgraded  MTX512 - the 256K Series 2 as well as the Memotech Videowall system based on the MTX512 S2.

As you can see from the photo, the MTX series oozed quality, it had a full travel QWERTY keyboard with separate number and function key groups and was mounted in a black, brushed aluminium case.

Even though you may not have come across this "Black Beauty" in the context of "real world" computing, if you've seen the 1985 film Weird Science, starring Kelly LeBrock as a computer generated "babe", and were particularly observant, you may have seen an MTX512 with FDX add-on star as Wyatt's computer, supposedly hacking into the Pentagon mainframe to create Lisa - now that is a weird idea, and not in the least far fetched :-)

- Lisa that is, not hacking into the Pentatgon, which well all know, could never happen!

You may of course, be more familiar with Kelly in the role of Charlotte in this pose (from The Woman in Red, 1984).



Picture reference:

Although the MTX series was technically superior to ZX Spectrums and the like, it was also comparatively expensive. As if that wasn't enough, the lack of games restricted its popularity with home computer buyers, this in turn made the software houses less inclined to develop new software which further limited sales....

A little history - The UK Home Computer Market in the early '80s+

In the early 1980s, the UK home computer market was booming, spearheaded by Clive Sinclair and the ZX80 released early in 1980 by his company, at the time called Science of Cambridge Ltd renamed, Sinclair Computers Ltd later that year. The Acorn Atom was released later the same year.

1981 saw Sinclair Computers Ltd renamed as Sinclair Research Ltd. and the ZX81 released in March, Acorn released the BBC Micro the same year.

In 1982, Sinclair released the ZX Spectrum which was joined by a glut of machines such as the Dragon32/64, Grundy Newbrain and the Jupiter Ace.

In 1983, came the Acorn Electron, Camputers Lynx, the Oric-1 as well as the Memotech MTX500/512.

1984 saw the entry of Amstrad into the market with the release of the CPC464 , along with the Apricot F1, Oric Atmos and the Sinclair QL.

1984 was the peak of the UK home computer market and the market had crashed by Christmas. In the previous year, retailers had underestimated demand and had not ordered enough stock to satisfy the demand that year. In 1984, determined not to make the same mistake again, they increased stock levels dramatically. By this time, the market was becoming saturated with home computers and demand had dropped significantly by Christmas 1984. Such is the power of the large retailers that the stock that they ordered was on a "sale or return" basis from the manufacturers. The retailers had over ordered for the 1984 Christmas market and returned large quantities of unsold stock to the manufacturers, hitting companies such as Sinclair, Dragon and Acorn, not to mention Memotech, very hard.

In order to get the best component prices, the computer manufacturers had long term orders with their component suppliers, placed at peak prices at the height of the home computer market. Other suppliers such as Amstrad were able to return a lot of inventory to component distributors, whereas Memotech, for example, had bought direct from factories in Japan and USA and was not able to return or decline delivery of any stock. This left the manufacturers with a large stock of surplus computers and component orders which could not be halted continuing to pour in which had to be paid for.

Amstrad became a major force in the marketplace after these events and, by buying components at what were in effect "fire sale" prices, they were able to offer the best price performance in the marketplace which sealed the fate of many of the early manufacturers, including Memotech and even Sinclair Research who sold out to Amstrad in 1986 for 5M - the same sum as Amstrad got for liquidating the old Sinclair stocks of computers.

The Memotech MTX range was also competing for the UK schools market, but this was effectively monopolised by Acorn Computers with the BBC Micro. They had the great advantage of the publicly owned BBC heavily promoting the Acorn (BBC) Micro for use in the nation's schools.

Given a level playing field, it is conceivable that the MTX range with its powerful hardware and software features could have made a bigger impact on the UK education market. As it was, because the BBC Computer had, in effect, locked out most other worthy contenders, Memotech had to reach farther afield in an attempt to get into the education market - i.e., the Russian schools bid.

By 1985, the UK home computer boom was over. Those computer manufacturers who had survived the carnage of the 1984 Christmas sales period quickly began to turn their attention away from home users to the growing and potentially much more lucrative business market. By then, the IBM PC had made a big impact on the business computer market and the popularity of CP/M had been surpassed by MS-DOS - the beginning of Microsoft's domination of the software market.

At the time, there was a US embargo on the supply of IBM PCs and/or the MS-DOS Operating System to the USSR, but CP/M was not included in the embargo.

The Russian schools system was looking to place a contract for systems in some 64,000 schools, to be used to provide education and training for robotics and control applications. In an attempt to secure the contract, Memotech worked with the Norwegian company, Norbit Elektronikk, to develop an add-on electronics unit to be offered alongside the CP/M based FDX disk system and with Oxford University to develop a Russian (Cyrillic) version of the system and BASIC ROMs, along with Russian documentation and keyboard. Memotech invested heavily in the development of this machine, but ultimately, lost out to Yamaha who won the contract with an MSX computer. This order was subsequently radically scaled back, only a few thousand were delivered, and the Russian government's aspiration to expand the use of computers in state schools faltered.

[You can read an interesting article on he Russian approach to "informatics" here, and more about the eventual winner of the school contract on this page. I have managed to dig out a few more of the details of the Russian schools opportunity - details on this page.]

By the time of the Russian bid, the writing was already on the wall, not just for Memotech, but for the majority of UK home computer companies of the time. The Russian deal was the last throw of the dice for Memotech and when it failed, Memotech had nowhere to go and the company was put into administrative receivership.

It can be seen that the MTX range was introduced at a time when there was an abundance of cheap, 8-bit, micros competing in an already saturated market. I think that Memotech were unclear themselves on what their target market for the MTX was; it was obviously intended to appeal to the "high end" home computer user, but with added peripherals like the FDX, was also intended to attract the business user too. Unfortunately, they did not manage to attract sufficient customers in either group, the machine was not commercially successful and the original company went into receivership at the end of 1985.

There are various articles on the web which state that Memotech produced about 250,000 MTX computers, this is incorrect. The 250,000 number may be close to accurate in relation to the number of ZX81 expansion modules produced (refer to the Home Computer Advanced Course item on Memotech on the Articles page), but is a gross exaggeration of the number of MTXs. Geoff Boyd estimates that the number of MTX500 and MTX512s was probably 10% to 25% of that figure.

Prior to their demise, Memotech released a range of add-ons for the MTX512, including the hugely expensive twin-floppy disc FDX system which ran CP/M 2.2 and supported an 80 column text board. The twin floppy version cost me 875 in 1984 and I still have it, after a prolonged period of not being functional, it is now well on the road to recovery.

I'm still a huge fan of the Memotech series and have collected as much information on them as possible - the menu bar on the left of the page will take you to a wide variety of Memotech related data from advertising material to hardware and software manuals. If you have any old MTX hardware that is in need of a new home, you might like to think about donating it :-)

Some of this information on this site comes courtesy of John Masterman who is no longer able to host this data himself but is happy for it to be made available to others - thanks John ! John still has a site dedicated to the Atari Portfolio which can be found here.

Thanks too, to Paul Daniels who has given me a load of scans of Memotech documents and a couple of MTX file utilities, and to Geoff Boyd for sharing his recollection of the Memotech days.

Other data I've picked up from various websites over the years - some of which are no longer around. If you recognise any of the data as yours and would like it to be accredited to you, please let me know, alternatively, if you object to seeing it here - please let me know to and I'll remove it.

Specifications - MTX 500/512

Processor  Zilog Z80A
Clock Speed  4 MHz (CPU) / 10 MHZ (Video Display Processor)
ROMs  24 KBytes

The first computers, using the 4000-04 version system board, had a 16KB combined Operating System (OS) and BASIC language ROM along with an 8KB Assembly language (ASSEM) ROM.

Later models, using 4000-05 and 4000-06 version system boards, had separate 8KB ROMs for each of the OS, BASIC and ASSEM segments.

Board Version 4000-04

Board Versions 4000-05 & 4000-06

ROM Location Size Function ROM Location Size Function
A 9H 16KB OS & A 9H 8K OS
RAM - fitted  32/64 KBytes
RAM - maximum  512 KBytes
Video RAM  16 KBytes of dedicated VRAM - ITT 4116 3N (see details)
Video Processor

 Texas Instruments TMS 9929A (UK/PAL) or TMS 9918 (US/NTSC)

This page describes how MTX video is generated in more detail and provides some hints on how to use your Memotech with modern TVs & monitors.

There is a good summary of the VDP on the Absolute Astronomy website here

There is lots of really good TMS 9918/9929 information available at, including lots of information from Karl Guttag, one of the designers of the TMS 9918.

The TI VDP Programmer's Guide can be found on the Technical Library pages

RF Modulator Output UK UHF Channel 36 or USA VHF Band 1 Channel 3 or 4 (User switchable)

 256 x 192 pixel resolution

 32 independently controlled user defined "sprites"

 Mode 0 (Text) : 24 lines of 40 characters (6 pixels/character) of text per line

 Mode 1 (Graphics 1) : 24 lines of 32 characters of text with graphics per line

 Mode 2 (Graphics 2) : 24 lines of 32 characters of text with graphics per line

Colours  16

 4 Channel, (3 independent voices plus 1 pink noise channel) (TI SN76489AN)

 There is a good technical page on programming the SN76489AN here.

I/O Capability  Z80 Bus, RF Out (TV), Cassette Interface (2400 baud), 2 Joystick ports, Hi-Fi out,   Composite Video out, Centronics Parallel Port, User I/O Port
I/O Options  Dual RS-232 ports, Floppy Disk Interfaces (FDX/SDX)
ROM Expansions  Node Ring (Peer-Peer Network), MTX Pascal, NewWord (Word Processor)
RAM Expansions  Additional RAM cards installed internally with 32K,64K,128K or 256K up to 512K max
Data Storage  Cassette Tape
Built in languages  Memotech MTX BASIC

See how Memotech BASIC compared against competitor machines of the time when running PCW Benchmark tests here. (2.9x faster than the ZX Spectrum).

 Built-in Z80 Assembly Language
 Front PANEL display for manipulation Z80 Registers and Memory
 NODDY - An interactive text manipulation language
Power Supply

External step-down transformer, 22.5 VAC 1A, tapped at 18V and 9V   

You can see the different models of PSU on Photos page.

Detailed technical data is available on the Power Supply page.

Construction The main system board was installed in a brushed aluminium case, with a full travel, 79 key, keyboard mounted in the upper half of the shell. The keyboard included separate numeric keypad, 8 function keypad and two blank keys either side of the spacebar, which, when pressed simultaneously, reset the computer. For the time, the keyboard was of a very high quality, and would, without doubt, have been a large contributor to the component costs.

Dimensions: 488x202x56mm          Weight: 2.6 kg

Internationalisation International character sets and appropriate keyboard layouts were available for UK, US, Finland, France, Germany, Spain, Denmark and Sweden. This appears to have utilised an additional ROM piggy backed onto the OS ROM and some custom wiring on the motherboard to make it work.

You can see photos of one example of this for a Danish MTX512 on this page.

Design Issues The MTX range was a great machine, but unfortunately, it did have a few issues that should have been addressed at the design stage :-
  • The horizontal screen position was displaced to the left, resulting in some/most TVs losing the left hand character off the side of the display unless the horizontal position was adjusted on the TV.
  • BASIC Error messages were very unhelpful, and, at least until familiar with them, many required the user to resort to the Operator's Manual for help in interpreting them, e.g. "SE.D" meant "Switch to absent Virtual Screen" - not very user friendly was it?
  • The position of the two reset keys on either side of the space bar was not popular with some users - it was too easy to reset the machine and lose your work.
  • The "Return" key was unusually small, particularly if you were a "touch typist".
  • When a BASIC program stopped, the last  few lines of the screen were cleared when the editing area reappeared. It was easy to program around this, but annoying all the same.
  • The machine did not produce proper circles - they were oval.

To my mind, though, these issues were minor when set against the other features of the machine described above.



As the ageing hardware fails, there are a number of ways that the MTX range is being kept alive through both software emulation and hardware projects such as Andy Key's REMEMOTECH.


The limited quantity of information available on the internet for these machines reflects their (lack of) popularity at the time. Some information is available on the sites below :-

Dedicated Memotech Site Links

Andy Key Andy was the author of some of the Memotech games, his site describes most, if not all of the Memotech range and includes much more besides.

Probably Definitely the most interesting Memotech related site on the internet, with quite a few hardware and software projects designed to breath new life into the Memotech name - go and look at it, you'll be impressed, both with the content and the Memotech inspired colour scheme.

memotech info  Jim Wills (Megastar Games) Memotech info site
mtxworld  Claus Beakkel's MTX Fan Page
mtxinfo  Peter Kretzschmar's site - lots of good MTX information
Sites Having Some Limited Memotech Content  A wealth of information about, as the name suggests, old computers.
Wikipedia  The Memotech MTX Entry on Wikipedia

Update: Since I drafted this page, there seems to have been something of a resurgence in the popularity of all things Memotech - or maybe I've just looked harder. Anyway, by following the links above, you should find a wealth of information on the MTX range.

A new MTX User Forum has recently started, it's pretty quiet at the moment, but would get busier with your support! - Check it out now at mtxworld!

The most lively Memotech place at the moment is the Facebook MTX500 Group


  +Some of this information comes courtesy of Geoff Boyd, 09/11/2012


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