My replica MK14 is based on the version 5 original, this version incorporates the revised address decoding so that the PROM only appears once in the memory map leaving space for e.g. the VDU board.
In addition I have added a link and pull-up resistor (R16) to NENIN for use with the VDU board (cut the link and fit the resistor) and a pull-down (R17) on SENSE-A which enables the use of the later version SCIOS (either fit the resistor or a wire link).
I have included three footprint options for the keypad switches:
5 x 5mm pads for the D6 switch (same as the reset switch)
7.62 x 10.16mm pads for Multimec RA3FTLx switches (with 1Kxx keycaps)
5 x 12.5mm pads the most commonly used footprint e.g. Omron M3F-40xx (with M32-13xx keycaps)
(replace xx in switch part numbers with your colour option)
Schematic
Bill Of Materials