This character keyboard is suited for word processors, CPUs, etc.
It has 3 * 18 = 54 keys, the preset labeling contains the characters A-Z 0-9 . , + - * / SPACE BACKSPACE SHIFT ENTER UP DOWN LEFT RIGHT and 4 empty buttons.
This is just the labeling on the signs, you can use the buttons for whatever you want.
The corresponding character code is programmed as an 8-bit wide value using levers (all levers are set to zero in the schematic, you have to program your character codes first before using it)
When a button is hit, the character code is buffered in an output latch until another button has been hit and the following circuitry is notified of the button event by a pulse on the yellow clock line.
Includes a fancy backlight.

Additional Notes

Blue: character code inputs (light blue indicates LSB)
Yellow: button-hit pulse output
Red: character code output (orange indicates LSB)