Re: Apple II Parallel Cards

[et472@FreeNet.Carleton.CA (Michael Black)]

"mdj" (mdj.mdj@gmail.com) writes:
> Michael J. Mahon wrote:
>> Greg Andrzejewski wrote:
>> > Were there any parallel interface cards made for the Apple II that
>> > completely adhere to the IEEE 1294 standard? Most of the ones I've seen seem
>> > to missing/ignore some lines (nERROR, nSELECT, etc)
>>
>> Apple parallel cards were designed before there *was* a PC!
>>
>> IBM chose not to adhere to the Apple standard.  ;-)
> 
> :-) and the 1294 standard was introduced about the same time as the
> first Pentium PC's in 1994.
> 
> I don't recall any of the parallel ports implementing bidirectional
> signalling, either. The exception would be the ProFile controller card,
> but this was not strictly speaking a parallel comms card of course.
> 
> Such a card could be very easily put together though - the PC style
> parallel port is a very simple interface. I seriously doubt though that
> the Apple II would have the processing power necessary to communicate
> in ECP or EPP mode with any peripheral that required it
> 
> Matt
> 

I didn't recognize the standard number, but it struck me that likely
it had come later.

Remember, the "IBM PC" parallel port was not two-way for a long time.
When people needed both ways (for non-printer use), they'd get by
with the input lines that were there (not a full byte's worth) in
the form of handshaking lines.  Or, one article (I think it was in
Micro Cornucopia), showed soldering some ICs onto a parallel card,
to add 8 bits of input.

You generally didn't need bidirectional on a parallel port, since
they were printer ports, and it was easier to use an 8-bit latch
than anything more complicated.  If you needed parallel input,
you'd buy a card that used something fancier, and it would be classed
as a parallel port, rather than a printer port.

Making the printer port bidirectional came much later.
 
  Michael