Re: Question about parallel card.

[Rubywand <rubywand@swbell.net>]

BabarStCyr writes ...
> 
> Hi
> 
> Are old parallel cards able to send AND receive datas?
> In others words can I do a LDA $CXXX to GET a byte?
> Are they any "standard" programming address for this type of cards?
>


     Most old parallel cards were printer interfaces. These need to be
able to receive two or three single-bit signals but do not need to
receive 8-bit data.

     When we built our own printer interface we used an 8-bit latch for
output and a 4-bit bus interface IC to receive signals (like /BUSY) from
the printer because it was cheaper and easier than mounting a 40-pin
multi-port I/O interface IC. It seems likely that most printer card
makers would follow a similar approach.

     One way to tell whether a printer or other parallel interface card
can be set up to receive 8-bit data is to check the IC's on the card. If
it has one of the standard 40-pin multi-port I/O chips (like a 6520,
6521, 6522, 6530, 8255, ...) there is a good chance that the board can
be set up to do 8-bit input and output.



Rubywand