> I can't remember how the Apple ][ centronics card does it. I remember 8
> outputs. I can't remember if that was 8 data bits and a strobe in
> hardware or 7 data bits and a software strobe (remember that 7 bits are
> enough for text characters). The busy input actually fiddled with the
> ROM addresses on the card, so the Apple executed different instructions
> when the printer became ready. Neat!.
Depends on the Card - some Cards used 6522 devices and here the
(programmable) handshake functionality of the 6522 was used. Some
cards had dedicated logic for unidirectional paralell output and
did the generation via a monoflop.
Gruss
H.
--
Ich denke, also bin ich, also gut
HRK
Received on Fri Jan 15 1999 - 07:57:46 GMT