IBM PC printer adapter schematic - test-drb@ccmp.vtda.org

8 Apr 2007

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Subject: Re: IBM PC printer adapter schematic
   From: "Ethan Dicks" <ethan.dicks at gmail.com>
   Date: Sat, 07 Apr 2007 18:29:29 -0500
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

On 4/7/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
  I wrote:
  That's handy to know - every once in a while,
I long for a machine
 with 2 or 3 parallel adapters, for things like old Connectix cameras,
 LCD displays and the like.  I've never assembled an ISA machine with
 more than one printer adapter.... 
 Well, you can have as may printer adapters as yopu like if you can set
 them all to different addresses and if you're writing your own software
 to talk to them... 
Naturally.  The problem I see is that only the older cards might let
you set the printer port to respond to arbitrary addresses - the ones
I have are almost (entirely?) all of the style where you move a single
jumper for LPT1 vs LPT2 (primary vs secondary address).

I wasn't as worried about the OS interpretation since I don't intend
to *print* to my printer port. 

The current system has three printer ports in it!  No big deal and there
are standard addesses that the OS (win or nt) recognize with no difficulty.
I use three as one is dot matrix (LQ570), one Laser (HP4l) and the third
is inkjet(color).   I happen to be using the a PCI, ISA and mainboard
based ports so where's the problem?

All the ISA cards I have allow for at least two if not many more possible 
printer ports. And same for serial, though after two the IRQ assignments
can be weird.

Allison