Why don't you use the nibble read to read the data?  Or you could even
do a byte read.  It is strange to find people still using the status
pins to read data from a device.  Especially when you can do byte read
and nibble reads without sacrificing no less that 4 input pins.

Also, a better interface with multiplexing is a solution around the 13
pin limit.  I have not seen this as a problem.

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Peter L. Peres
Sent: Thursday, September 19, 2002 3:34 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: Printer port control software

On Wed, 18 Sep 2002, James Williams wrote:

*>No, you are wrong it does not have to be EPP compatible.  Only SPP
which
*>is compatibility mode, nStrobe signal, nBusy and nAck signals for
write.
*>You can also do nibble read.  The point is it DOES NOT HAVE TO BE A
EPP
*>device.  As long as your device does the following:
*>1.  Responds to an nStrobe negative pulse.
*>2.  Bring nBusy high in response to step one.
*>3.  Finally pulse nAck and bring nBusy low.

Okay, I will try it out next time. But I see it as three pins on the
interface, wasted. There are only 13 of them so this is a significant
loss. I have made several parallel controlled devices in the past, that
cannot dispense with these three pins.

Peter

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