help needed to restore cortex to working condition
HI,
I have a cortex that I built in the 1980's.
Its been in the loft for 20 years and I have often thought about trying to get it working.
any help or encouragement would be great.
it has the later Maplin display board and 256k of ram with the ls2001 replacement header and the eproms were reprogrammed for the later disk drive chip ( changed them to a 2764 on a header board)
I do hope to hear from someone that has a working machine.
You've probably got the most advanced machine of all of us. Me, & AndyP have working machines in the UK (although we both seem to have slight sync problems in that the leftmost side of the display is a bit hidden) I have a floppy on mine, but the cable's damaged & I'm waiting till I have a few bits to order before getting a (few) replacement IDC sockets. Have a look back through the thread.
I'd be inclined to test the PSU separately (with a dummy load (car bulb or something)) before connecting to the logic board, also do a shorts test on the power conections to the main board. Usual faults for a machine that hasn't been powered up for 20+ years are dried out power supply electrolytics (ripply outputs & occasionally a minor explosion), Tantalum capacitors on the PCBs shorted out (shorts the power supply & can burn tracks off the pcb, sometimes there's one on the reset, which stops the machine resetting), oxidised I/C sockets (cured by removing & reseating chips), damaged memory (caused by cosmic rays!), and dirty/oxidised keyboard contacts.
We'd love a dump of the roms, & if these quick notes go over your head, we're happy to help further!
"Don't it always seem to go
That you don't know what you’ve got ‘til it’s gone" (BANG)
right then....all i need to do is get the workshop sorted out and explain that I am hiding in the loft trying to ressurect a machine hedden there for 20 years of marriage...should be easy !
seriously I will try to test the PSU and check out the machine, last I tried it just sat there but the voltages were fine, might head for the reset switch and see if the cap has gone short ! probably be a few weeks beofre I get a chance but great to hear that I do not have the last one.
There are links above to the whtech archive which has software, schematics & reprints of the original ETI articles etc. I can't be bothered going back through 23 pages though!
I've done a proper loft conversion now, there's no way that the CDC 14" disk drives would go up a ladder, I was worried about the stairs with 2 blokes and over a hundredweight of drive between us. Next house has to have a semi-basement, so I can get to use the (about 1/4 ton of) band-printer.
"Don't it always seem to go
That you don't know what you’ve got ‘til it’s gone" (BANG
Excellent! We seem to have found another Cortex userWelcome!
I've been pretty busy of late, but I will try to get the games Andy sent me up onto WHT this weekend.
when I first built mine it had the display too far to the left...
are you on a RGB set up or the modulator ?
Mine hasn't got a composite/rgb output (it has a hole in the case for a din socket, but nowhere on the board (or the schematic even!)for it to connect to) purely a modulated output.
you say "when you first built it the display was too far to the left", did you correct this? it looks like it could be firmware correctable.
"Don't it always seem to go
That you don't know what you’ve got ‘til it’s gone" (BANG
It's a long time ago but I remember taking the video connection from the input of the modulator and using this for composite to a TV...I think I used a couple of transistor stages to buffer it and drive it.
Some where i thnk i have the user group news letter with the "official" RGB interface and maybe even a copper diagram for the board...Will have a look next weekend.
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