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1980s Computers Explanation of terms

The MTX-500 Series



Memotech (UK)


MTX-500 and MTX-512

Date Launched

June 1983


£275 MTX-500
£315 MTX-512

Microprocessor type

Zilog Z80A @ 4 MHz

ROM size

24 kilobytes
(8 KB each for the operating system, BASIC and assembler)

Standard RAM

32 kilobytes (MTX-500)
64 kilobytes (MTX-512)

Maximum RAM

512 kilobytes using two internal expansion boards

Keyboard type

Good quality typewriter-style.
An unfortunate feature of the design was that there were two unmarked keys either side of the space bar (where the Alt keys are on a PC keyboard.) If these were pressed simultaneously the machine was reset, losing any stored program.

Supplied language

Advanced BASIC
Simplified 'Noddy' language

Text resolution

40 x 24 characters

Graphics resolution

256 x 192 pixels

Colours available

Some restrictions on colour of adjacent pixels

Example Screenshot

MTX 512 display
A shoot-the-aliens type game on the MTX 512, looking very similar to Timegate for the Sinclair Spectrum.


3 channels through television

Cassette load speed

2400 baud
Lower speeds optional

Dimensions (mm)
Weight (grams)

488 x 202 x 56
Not known

Special features

Had a black anodised aluminium case.
With 64 KB RAM it could run the CP/M operating system.

Good points

Ports for printer, ROM cartridge and joysticks.
Powerful graphics and sound commands in the BASIC.
32 graphic 'sprites' for games.

Bad points

Expensive compared to most other home micros of the time.
Despite having the same processor as the ZX Spectrum and a similar display, not many games were written for the MTX series.

How successful?

More popular than most of the second wave of 8-bit home computers and about 250,000 were sold. However by mid 1983 the home computer market was becoming saturated and it was difficult for any new design to find a niche.
The range was withdrawn in 1985.


The only difference between the 500 and 512 was the amount of supplied RAM.
Memotech previously made well-regarded peripherals for the Sinclair ZX range before introducing their own computers.
The MTX series had a high specification and the built-in assembler and disassembler appealed to the (fairly small number of) users who were interested in writing machine code programs.
There were some faults with the MTX design which should have been corrected before it was launched:

  • The horizontal positioning of the screen display was wrong, causing the first letter of each line to be off the left hand edge of the screen on some televisions.
  • The BASIC error messages were just codes which had to be looked up in the manual.
  • The editor for entering BASIC programs was poor compared to the competition.

Like many of the new computers brought out in 1983-1984, the MTX was not sufficiently better than its rivals to tempt too many people to risk buying a machine with limited software support.
Read more on the MTX-500.

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