PS2 keyboard for Atari 8-bits

[foft]

Is it possible to interface a keyboard with just 3 lines, high bit scan counter (k5), kr1 and kr2? Using the high bit to sync a counter? Just thinking that might simplify the install.

[+mytek]

Is it possible to interface a keyboard with just 3 lines, high bit scan counter (k5), kr1 and kr2? Using the high bit to sync a counter? Just thinking that might simplify the install.

Theoretically that should work. The AKI/KRH did something like that with two of the counter bits, and it would seem like it should be possible to sync an internal counter on the arduino to only one bit. Just a matter of using a prescaler for one of the internal counters and dependent upon its range, pick a corresponding master clock that yields the same clock rate as the Pokey key scan counter.

 

I actually should have done that for the TK-II, but I got lazy.

[znac049]

Is it possible to interface a keyboard with just 3 lines, high bit scan counter (k5), kr1 and kr2? Using the high bit to sync a counter? Just thinking that might simplify the install.

Possible, yes, but not sure what it buys you. On the plus side, yes, you save some I/O on the microcontroller, but you have to weigh that against the opportunity it creates for the counter to get out of step with K0-5. Unlikely, I know if the software is properly written, but as everyone will tell you, "Software always lets you down!" I don't see how it simplifies the install as all of those signals are straight from the POKEY so directly accessible on the POKEY daughter board.There is enough I/O on the ATMEGA328 so no problem. The "keep it simple" principle wins out here, I think.

 

-Bob

[znac049]

Hi Michael,

 

Another question, I'm afraid - I want to be as compatible as possible with TK-II, so what is your approach to mapping keys where a single key on the PS2/USB keyboard maps to two different keycodes on the A8? For example, the '=' key when shifted yields '+' on the USB keyboard, but on the A8, these are different keys. My solution so far is to emulate an unshifted '+' key on the Atari, but that, in theory, could break software that's doing its own keyboard scanning. I could toggle the behaviour through a EEPROM seting. Also, how would I then send the equivalent of a shifted '+' Atari key?

 

Thanks,

-Bob