Re: Apple II Parallel Cards

["Michael J. Mahon" <mjmahon@aol.com>]

mdj wrote:
> 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

There were one or two parallel port cards (intended for printers)
that used a 6522 VIA.  That could in principle provide bidirectionality,
though I doubt that any were actually wired and programmed to do so.

The real determining factor for the Apple parallel printer interface
was the _de facto_ Centronics interface, which most printers used.

IBM followed suit with the PC, and it wasn't until printers got a lot
smarter (LaserJet) that bidirectionality (other than handshaking and
error signalling) became an issue.

-michael

New, faster SUDOKU v2.0 solver for Apple II's!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."