Heavily Customised TS1000 in ZX81 case: Part 2

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Australia The Clueless Engineer
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Published on ● Video Link: https://www.youtube.com/watch?v=tdTu4gKl1bc


Duration: 19:04
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In this video I take a look at the beautifully constructed, wire wrapped 16KB DRAM expansion board that accompanied this US ZX81.

It comprises the following:
8 x MCM4116
1 x 74LS00 quad NAND
1 x 74LS32 quad OR
1 x 74LS393 dual 4-bit counters
4 x 74LS157 quad 2-input mux

I'm guessing the design closely resembles the Sinclair 16KB RAM pack, just by a quick look at the components - the original uses the 9V from the ZX to generate the -5V and +12V voltages:
https://www.myprius.co.za/ZX81.htm



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