ZX80 and ZXCCB

[1024MAK]

For RAM pin-outs, follow the link in my sig.

Mark

[beanz]

Hard to say so far away.
The 2114 RAM chips have 5V at pin 18. Usually pins are marked in anti-clockwise manner, beginning from pin 1 at the lower left corner when you read the name of the IC. Pin 18 is then the top left pin. As far as you get a cursor or something similar and as it moves when you press a key - the ZX80 seems to work in general. There may be an issue with the output video signal. Harder to find without an oscilloscope. You could check if R30/R32 are correct and have connection as schematic. It may be, that the video output is missing and just the sync output here which would result in a picture with a black box cursor (no white K inside) - this maybe hard to find out if not correct tuned in and picture very unsharp.

You may check if pixel data is coming out of the shift register and if the connection A-C or A-B is present. Normally hardcoded on the ZX80. Did it work before ? With which modulator ? There maybe differences between the modulators of ZX80 and ZX81 in video levels.

It worked with the original modulator in it (at work at moment so not sure what it was, I'm pretty sure it was the same modulator as the model in the ZX81. Wouldn't be the first time something died on me while I was fiddling with it though .

Thanks for the info, I'll measure voltages etc and see if anything weird shows up...I assume though a good voltage meaure on the ICs doesn't necessarily mean it works though huh..it could still be bad.

[gozzo]

er..one thing, exactly how have you wired in the ccb module.....