Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!nosc!ucsd!ucbvax!MITRE-BEDFORD.ARPA!jhs
From: jhs@MITRE-BEDFORD.ARPA
Newsgroups: comp.sys.atari.8bit
Subject: Re: (Parallel) Centronics (Printer) ports for the 8-bitters...
Message-ID: <8808091926.AA09370@mitre-bedford.ARPA>
Date: 9 Aug 88 19:26:54 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 26

I agree, the best known choices are Atari's own 850 interface, usually sold
for $109 but apparently available used for $89 if you are lucky, and the ICD
P:R:Connection.  There's also one called the ApeFace, which is strictly a
parallel printer port.  The Atari 850 indeed has 4 serial ports as well, and
the P:R:Connection has two of them.

I have seen at least one disk drive (the Trak) that has a built-in printer
port.  I think others (Supra) may also.

For all of these, the built-in P: driver and the LPRINT command in BASIC
work perfectly normally.  You would not have to mess with writing a custom
driver.

Finally, a lot of people have built up their own interface to run a printer
off the joystick ports.  These are basically the Data lines of a PIA chip,
and can be programmed to be outputs, although they are normally set up as the
joystick inputs.  I haven't seen the details, but the trick will be to derive
a strobe line to tell the printer to read the data.  It has been done, so if
you can think up a scheme or find out how others have done it, you can build
an interface with almost no parts in it, i.e. just the logic for the strobe.
For this approach, you WILL need to write a driver, and if you do it right,
the method should look like a normal P: device to the calling programs,
including BASIC, meaning that LPRINT will still work.  Of course, you would
probably have to unplug the joysticks, or at least provide a switch to select
joysticks or printer.

-John Sangster / jhs@mitre-bedford.arpa