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Hi Jeff,

The fault is still as posted in my second post. That is as follows:-

Switch the unit on, and I get the usual screen full of misc characters. Press the reset keys, and sometimes I will end up at the 'boot screen' with the startup message, sometimes the computer refuses to acknowledge the reset, although the reset line to the 6502 does go low. I can get to the monitor prompt probably 1 time out of 5 that I reset.

Turn the board the wrong way up, so that the keys are facing down, press the reset keys, and the monitor prompt appears probably 3 times out of 5.

This now suggests an intermittent key switch, or something associated with the keyboard scanning circuitry.

Regards,
Mike

Once you do succeed in doing a reset, will it then do a full cold start and run basic?

I think you should get the MON prompt even with stuck key ?

Hi Bill, Mike,

Yes, once it completes a full reset, I choose 'C' for a cold start and can run BASIC.
Unfortunately some of the key presses give occasional incorrect characters.
UPDATE.....
Scoping the inputs to the 2 74125's gives some unexpected variations in amplitude of the key scan waveforms. Further testing has revealed that 3 of the 4.7k pull up resistors have changed value. If the board is flexed whilst checking the resistance, it varies from 4.7k to over 100k. Replacing all 8 resistors, appears to have solved the problem, whilst earlier checks of these did not reveal any fault. It seems that CompShop supplied some poor quality components when they put these kits together.

Success at last...
Reset,OK
Cold start, OK
Operate all keys, correct characters appear on screen.
Type in a small basic program, type run, press enter, program runs successfully.
I can even load and save by using a pc as the serial device via the acia.

WooHoo, I have a working Compukit UK101.

I think i'll play with it in this condition for a while, then possibly modify it again, and see if I can get it to run with a replacement WEMON monitor rom.

Now to try and find a replacement caps lock switch as the lock has failed.

Thanks for the suggestions guys,

Best regards from a happy UK101 owner.
Mike

Congratulations Mike!

Well done Mike.
I had a peek at Comp Shop on Google maps. Doesnt look like you will find caps lock key there now !
On to the Kim ?
Will be interested to see your progger design. Do you have any software or other hardware for the UK101 ?
In particular I am looking for info or manual on Premier Publications BASIC 5 ROM. They used to advertise in Practical Electronics. The ROMS are on Daves site if you want to add them to your 101. Toolkit is quite handy.

Please add a harware/software profile via the Conrol Panel so us old fellas remember what you have.

Mike

Great news getting it working!!!

/Jeff

Nice! Congratulations.

Hi Guys,

Thanks for the encouragement and useful suggestions.

Now that the UK101 is working again, I'll have to dig out the external memory board that I purchased second hand in 1982. I have no idea if it works, or what it was based on. It has a label on it marked 'SMART 2', but without a manufacturers name. If / when I find it , i'll upload a couple of photo's and see if anyone can identify it.

@ MK14HAK
Mike, I have added a hardware profile as requested. Sorry no software, all original cassettes have been lost in the mists of time.

Regards,
Mike

Mike, are you near this interesting looking vintage computer museum at all : http://www.computinghistory.org.uk/det/ ... wsletters/

I believe they loan gear out. I used to have those UK newsletters but they are lost in the mist too. Would be great to get scans of those for Daves collection ....

Mike 52 ++