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1980s Computers Explanation of terms

The Cortex



Powertran Cybernetics (UK)



Date Launched

1983 ?


£339 as a kit.
£454 ready-built.

Microprocessor type

Texas Instruments TMS 9995 @ 3 MHz
(A 16-bit processor similar to that used in the Texas Instruments TI 99/4.)

ROM size

24 kilobytes

Standard RAM

64 kilobytes plus separate 16 KB video RAM.

Maximum RAM

Possibly 256 kilobytes

Keyboard type

Typewriter style with numeric pad.

Supplied language

Quite advanced BASIC plus an assembler/disassembler.
Forth was available as an extra.

Text resolution

40 X 25 characters

Graphics resolution

256 x 192 pixels

Colours available

There must have been some trade-off between resolution and number of colours.


Through internal speaker.

Cassette load speed

Baud rate was selected by the user.
One or two internal 5¼ inch floppy disk drives were optional.

Special features

Floating point numbers were handled using 48 bits, giving 11 decimal digits of accuracy – better than most other BASICs.
The character set could be redefined.

Good points

A large amount of available memory.
Sturdy metal case.

Bad points

There was no serial, parallel or monitor interface as standard (they were extra) – this was unusual for a relatively expensive machine.

How successful?

Sales seem to have been quite low.


The Cortex was promoted by the magazines Electronics Today International (who published assembly instructions) and Computing Today.
It is not clear what market the Cortex was aimed at. It was too expensive for the home, games-playing sector and was priced towards the low end of the business computer market. However business computers mostly used Z80 microprocessors running CP/M, or the newer 8086 processor running DOS.
Whatever the technical merits of the TMS 9995 16-bit processor there was very little software available for it, plus business customers would expect at least a parallel printer interface and probably a monitor output and 80-column display as standard.
The Cortex may have appealed to the electronics enthusiast but it was expensive for just tinkering with.
The later Cortex II used the same hardware but in a more contemporary beige plastic sloping case.

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