Re: Apple II Parallel Cards

["Greg Andrzejewski" <pressyourluck85@yahoo.com>]

"mdj" <mdj.mdj@gmail.com> wrote in message 
1157074498.502604.280610@b28g2000cwb.googlegroups.com">news:1157074498.502604.280610@b28g2000cwb.googlegroups.com...
>
> Greg Andrzejewski wrote:
>
>> Exactly. I/O from the parallel port doesn't require ECP/EPP. On IBM's 
>> SPP, 4
>> status lines are used to read a nibble from a device (creatively termed
>> 'nibble mode'). A decent description can be found here
>> http://www.fapo.com/nibble.htm. Using nibble mode allows the SPP to
>> interface with more than just printers (tape drives, scanners, zip 
>> drives,
>> etc).
>
> This is the old HP Bitronics mode. In theory the cards Michael
> mentioned have the means to control such devices, assuming all the
> control lines are wired.

Yeah, that's the thing. I've been looking at pinouts of different Apple II 
parallel cards and they all seem to be missing one or two control lines 
present on an SPP. The decision then become whether to try to modify an 
existing parallel card or (gasp) try to create my own.....

-Greg
>
>> The problem is the lines used by nibble mode aren't present on most Apple 
>> II
>> parallel cards. If there was a card that effectively duplicated the 
>> function
>> on an IBM SPP, all that would be needed to take advantage of so many
>> parallel I/O devices being dumped daily is appropriate software.
>>
>> Thus answering the question that prompted this inquiry, "Why can't I use 
>> a
>> parallel zip drive with my Apple IIe?"
>
> The software would take some writing, but it's possible. Essentially
> you'd need a loadable driver than parked itself in one of the upper
> banks of a RamWorks card and patched itself into ProDOS as a SmartPort
> driver. Doable, but tricky. It's far, far easier to use SCSI for this,
> and the SCSI cards are probably more common than the parallel cards
> that provide sufficient signalling.
>
> I'd like to see it done though, if just for the 'cool' factor.
>
> Matt
>