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LDO regulator 3.3V is not required, so it can be jumped with 0Ohm resistor.
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CLK on ZX BUS edge connector is not inverted. This can cause problems on ZX Spectrum peripherial devices that uses clock to sync, like DivMMC, etc. Possibly fix: cut the track from ZX BUS edge connector and route Z80_CLK (from Z80 pin 6) via one of the free inverted hex buffer IC4 (pins 5,6 for example).