- off-by-one connections to keyboard connector
- wrong demultiplexing of select signals
- 2OE on 74LS240 was not inverted, resulting in wrong circuit.
- use pre-jumpered row diodes.
- fixed off-grid errors on schematic
- replaced DIP header with 13-pin 0.1" vertical header. Added labels to
the pins.
- removed left over unused diode
- reversed default on / default off labels on shiftlock mode jumper
block.
- Moved header slightly forward
- Moved interface mount holes do reduce interference with case mount holes
- For all keys in classic keyboard, add option for either through-hole or SMT
diodes and resistors.
- adjust RC constants to use simple, common values and reduce number of
different part values.
- Create add-on PCB to provide reset/shiftlock function for older 542 and SB2
keyboards.
Provides a keyboard interface to interface with OSI computers. Equivalent to an
OSI 542C.
- Includes sound circuits
- Includes RESET delay circuit
- SHIFT LOCK can be mechanical push-on/push-off or soft toggle, selectable by
jumper.
- Provide SHIFT LOCK LED output.
