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Sinclair ZX81 Troubleshooting Guide: Revision history

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23 September 2026

  • curprev 22:3922:39, 23 September 2026 Josh talk contribs 10,824 bytes +17 House style: state the correct figure and the trap, not what an earlier revision of the page said undo
  • curprev 20:1720:17, 23 September 2026 Josh talk contribs 10,807 bytes +3,775 Corrections from Sinclair's own manual and circuit diagram: the CPU clock is 3.25 MHz on every issue (page gave 3.5 MHz for Issue 2, a Spectrum figure); the ZX81 supply IS unregulated by design (page said never to use an unregulated supply); the ROM is a 24-pin 2364 and a 2716 cannot hold it; the 4118 is 24-pin, only the 2114 pair is 18-pin; video capacitor is C1 not C5/C6, and the tape capacitors are C10-C12 not C8/C9; modulator drive is ~2 V peak not 1 Vpp; remove the unsupported ULA-to-boa... undo

12 May 2025

4 May 2025

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