ASCII Keyboard (Electron)

Based on the issue 4 schematic, the original System keyboard had a latching CAPS LOCK key switch, these are hard/impossible to find and so an alternative electronic implementation has been made using a second 555 timer (IC8).

The keyboard requires a donor Electron computer case and keyboard as well as a set of BBC computer keycaps (the original Electron keycaps could be used but I don't think they look as smart).

The Electron keyboard mounting plate needs to be modified to allow for the repositioning of some of the keys:

The Electron case requires modification to allow for the extra keys and holes drilled for the LEDs, the board then directly replaces the original Electron keyboard PCB.

The links have the following functions:

• LK1/2 - inverts the Strobe output, normally left with LK1 open, LK2 closed

• LK3 - bypasses the Break/power-up-reset circuit (IC7), normally left open

• LK4 - inverts the CAPS LOCK function, normally left with 1-2 linked

Schematic

• ASCII Keyboard (Electron) Schematic

Bill Of Materials

• ASCII Keyboard (Electron) BOM

Blank PCB

Assembled PCB (no key-switches)

Assembled PCB (with key-switches)

Rear View

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