Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
Oooh... That one looks beaten up. Is it still working though? And a weird heatsink indeed. Guess it won't hurt. Mine is running quite warm.
Just checked the PCB manufacturer and if I order 5 or more boards, the PCB costs around 9,60 euro. Toughest part is finding the 2114 RAM chips. I still have a few of these left.
Your W buttons are upside down! They should be pushed up through the bottom of the case I believe
Thanks for that!
I think I may have found a similar rivet here:
http://www.essentracomponents.com/en-gb ... ter=5.8-mm
Requested a free sample, so let's see!
I do sell replacements for the ZX80 case rivets which may well be the same size...
But a free sample is even better
Thanks! Actually got my original version today! And I am still surprised about the markings on the chips. Each 1K of RAM consists of 2 of these chips. One for the high nibble, the other for the low nibble. But why is one half done with an 2114LC and the other with a 2114LC-1. The -1 version has a 300ns access time, whereas the unmarked is 450ns. Same was done in the original ZX80.
The only thing I can think of, is because of dataline D6' that is used in the NOP code generation during video display and has to be fast enough. That's probably also the reason why it is the only dataline with an additional pull-up resistor to speed it up a bit more. The slower device is less critical and was probably cheaper. Please correct me if I'm wrong
Time to test it and give it a nice bath of RetrObright..
Anyway, here are some side by side photos.
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At one time RS branded their "RS" logo on all manor of electronic parts and equipment. I've got various chips and other parts with the RS branding.
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