There are plug-in boards that provide an extra SPP/EPP/ECP port, which is
safer than simply using the motherboard-resident one. That would be less
trouble if you were to break it than would be the one on the motherboard.
The EPP port is more desirable, IMHO, simply because it isolates your
"hobby-project" from the inards of the computer. It also provides a handy
connector, and a simple protocol by which to provide yourself with up to 256
I/O ports in either direction, without having to open the box except to plug
in the parallel port card. If one happened to come with a DLL with which
you can write WINDOWS code for your port, so much the better!
One rather important aspect, of course, is that the printer port can really
drive the properly terminated cable, while a "normal" MOS LSI for parallel
I/O, e.g. 8255, 6821, etc, can't.
Dick
----- Original Message -----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Thursday, June 08, 2000 3:50 PM
Subject: Re: Wirin' up blinkenlights
> >
> > Here's a question for the group. I have a PC running Bob Supnik's
PDP-11
> > simulator and a PDP-11/45 front panel with no CPU boards. I'd like to
do
> > sort of a faux PDP-11/45 with this setup by somehow wiring the front
panel
> > up to the PC running Sim.
> >
> > Am I completely out of my mind, or is there even the remotest chance of
>
> We're all out of our minds on this list ;-)
>
> > getting something like this to work?
>
> It's _possible_. It's probably less work to find a set of 11/45 CPU
> boards and get them working, but it's still _possible_ to do what you ask.
>
> The hardware shouldn't be too bad. The 11/45 frontpanel board is just the
> lights, switches, and lamp drivers IIRC. So you'd need to provide :
>
> Power supplies (+5V for the logic and +15V for the lamps IIRC).
> Input ports on the PC to take inputs from the switches
> Output ports on the PC to drive the lamps.
>
> You could either build your own I/O port cards using (say) the 8255
> chip, or buy them ready made ($$$ since they don't sell in the quantities
> of most PC bits), or with a bit (OK, a lot) of logic, hang the whole
> thing off a printer port.
>
> Then you have to modify the simulator to talk to these I/O ports. Just a
> Simple Matter of Programming (tm). Eeek!
>
> -tony
>
Received on Thu Jun 08 2000 - 17:31:36 BST