PS2 to ASCII interface work

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Since I didn’t get the new caps and transistors yet, I went to work on the PS/2-ASCII interface. Well except for an issue with booting up reliably, it seems to be working. I need to work on the AVR fuse settings for power up and/or add power on reset circuit.

PS2 to ASCII adaptor test setup

For the Apple-1 clear function I added a diode to the AVR’s output, similar to what is seen on the input to D15, pin 9. This is necessary because there is another TTL output that can drive this signal.

PS/2 to ASCII adaptor

The three jumpers on the right side of the board are to disable/enable the following functions.

  • enable automatic arrow mapping to Apple 2 – ESC-char cursor control sequences
  • enable inverted data – not needed for Apple 1 or Apple 2, but added in case some other vintage computer needs inverted data
  • enable/disable Control – RST and Control -CLR – reset and clear screen sequences

    • There are several options for mapping the wiring from 16 pin dip ribbon cable to the AVR.

  • It can be wire wrapped as I did on my prototype
  • The header can be left off and it can be done directly with jumper wires
  • You can build a plugable jumper block in a housing that plugs onto the header