| ZX81+38 Build [message #7908] |
Tue, 11 August 2020 22:49  |
ale500
Messages: 44
Registered: April 2018
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Using the info available here: https://revspace.nl/ZX81plus38_simple_to_build_ZX-81_clone I decided to get some boards made and order some parts (mostly from ali) and get (again) a ZX81 working. This is a computer I had as a kid, well a Brazilian clone called TK-85. We had quite some fun even if it was b&w and without sound.
The boards arrived some week ago, I got 5 made and populated one. Most chips I tested with a MiniPro and for the Z80 I made a breadboard SBC. Yesterday I finally got the crystals and the first very funny issue appeared (I should have got all parts from Reichelt, I know). The oscillator produces a square wave of only ~30 kHz !... never seen that. The crystals are from Mouser. Nonetheless It seems to work, it produces the video signal and one can see that the processor runs and memory gets checked but at snail pace (the Z80 is a CMOS version).
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