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This mini forum is intended to provide a simple means of discussion about the Powertran Cybernetics  CORTEX computer. If you want to share your own experience or memories, or add relevant information about this system: post a message!

  Click Here to add a message in the forum


Thursday 15th October 2020
Dennis Johnson (Wales/UK)

I built a Cortex back at end of 1982 when it came out in the magazine Electronics Today.Being a keen electronics hobbyist,it looked like the ideal thing for me to get my teeth into.I trained in the early days on Digital PDP8 and 11 linked to engineering equpment.I did a lot of machine code writing for the Cortex and wrote games like Othello,Mastermind and mazes etc.
My machine now needs some tlc,which it will have even though it still works fine.At the time I built it,it was way ahead of its time and really fast with "sprites"that could be moved around the screen.
Not quite sure what to do with it now as space is somewhat limited in new home.

Monday 15th June 2020
Joe Mc (UK)

Hello, I still have a brochure for a "Powertran" PSI COMP 80 (Z80 based computer). The keyboard looks exactly the same as the one in your small pic but it has a hex pad where your pic has a numeric keypad? I think I have details of a precursor to the one you have presented. If you would like, I can scan and email the pages (7 of them). Kind Regards Joe.

Friday 4th January 2013
Jim Hearne (UK)

I have a Cortex 2, built from old stock kit last year. It''s running complete with the FDC and dual 5.25" drives from a BBC computer. If you have the missing copies of the Cortex user group magazine please visit and let us know.


Thursday 4th November 2010
FreeThinker (UK)

The ETI article for the cortex can be found here$20Cortex
also includes an emulator, Roms etc.

Monday 31st May 2010
david loudfoot (uk)

HI, I still have my cortex stored in my loft in essex but at the moment it is not working, would love to get it up and going again.

Monday 24th May 2010
Chris Followell (UK/ Spain)

Hi Guys, I worked for TI at the time and of the Cortex. I was the sales engineer for the Cortex components (TMS9995 CPU and TTL and DRAM. I co wrote the Electronics Today International Article along with Neil Quarmby, the TI project manager for the Cortex. The case PSU etc were all done by Powertran, we at TI just did the motherboard and the software. I still have my copies of the three issues of the magazine, so if anyone wants me to scan them, just say pretty please and I will do it when I get a free moment. It was a fun project and of course was well ahead of its time, being a 16 bit CPU in the days of 8 bits. We used the same processor for the first Viewdata (Prestel) decoder boards. With V23 Modems (1200/75 - good grief!) The US Home Computer division also used the 9995 - whereas Sir Clive was still using the Z80!

Saturday 13rd June 2009
Dave Hunter (Ft Lauderdale, Florida, USA))

I have two of these. Both work, have disk drives and the V9938 MSX Video Chip. I have both the CDOS and MDEX Operating Systems. CDOS is the Disk Filing System extension for the built-in Cortex Basic. MDEX (Marinchip Disk EXecutive) was the first Disk Operating System and was quite simple. It over-wrote Cortex Basic at boot so you couldn''t use any programs developed in its native environment. However you also could buy QBASIC (Basic compiler) and SPL (Sytems Programming Language compiler), the latter was somewhat similar to C. I have lots of knowledge on this computer and have posted some info over at under the name of ''tms9995''.

Saturday 9th May 2009
James Fetzner (USA)

I finally acquired a functional Cortex after a long search (many years, off and on). It only has the cassette interface installed, but I plan to try and finish the disk interface. I also noticed that the documentation I received with mine has several pages that aren''t in the documentation included on the site. I will try and rectify that once I can get the additional pages scanned.

Friday 20th March 2009
Anders Carlsson (Västerås, Sweden)

The Swedish electronics magazine Elektronikvärlden in late 1983, early 1984 also had a series how to build the Cortex computer, probably they translated and reprinted the UK articles. Some readers got so involved they even posted follow-up questions about the project.

Sunday 23rd September 2007
Magne Ertresvåg (Ålesund Norway)

I still have the Cortex, but I haven't powered it up for years. It was fun to program. Are there anyone how still got a Cortex, or have you dumped years ago?

Friday 6th April 2007
Chris Haywood (UK)

I have one of the Cortex computers which I built when I was studying for my electronics degree in the UK. The machine was pretty unreliable until my "mentor" engineer helped me figure out the the DRAM (64k chips) power supply was noisy. Once the supplies were gridded it worked really well. I could not afford the floppy drives so I used a cassette tape recorder connected to the modem port to save and load programs. If I remember correctly it was the first computer to have graphic "sprites" which were pixel objects that you could move around as a block across their own graphics plane - I think that there were 32 planes altogether.

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