blinkenlight console - not only for PDP's !

From: Gooijen H <GOOI_at_oce.nl>
Date: Tue Apr 13 07:05:00 2004

  Hi all,

I finally had some time to work on my "homebrew console" project.
It is not yet finished, but the progress is significant enough
to report to this group.
I completed the wiring of the new sleak design PDP-11/35 console,
and debugged the "firmware" of the Motorola M6802 microprocessor.

After the console seemed to work as I wanted it (...) [using the
built-in debug monitor], it was time to turn to the current SIMH
version (3.2-0). I ported my previous thoughts of version 2.10 to
this current release, and debugged a little more :-)

The progress so far:
1) set the switches to any address, press "LOAD ADRS".
   result: the position of the switches appears on the ADDRESS LEDs.
2) set the switches [15:0] to any value, press "DEP".
   result: - the data is stored in the (previously loaded) address.
           - the data appears on the DATA LEDs.
3) press "EXAM"
   result: - the address is shown on the ADDRESS LEDs,
           - the data of this address is shown on the DATA LEDs.
4) when "EXAM" is pressed again after "EXAM"
   result: the next address is shown (address and data)
5) when "DEP" is pressed again after "DEP"
   result: the data is stored in the next address.
6) when "EXAM" and "DEP" are toggled following each other
   result: the address is not incremented.

So, LOAD, EXAM, and DEP react as the REAL CONSOLE in combination
with the patched SIMH software ! More testing will be done.

I thought this progress was nice to mention here; the following items
on my list are:
- behaviour of CONT, HALT/ENABL, START (and S-STEP!)
- ADDRESS and DATA LEDs update automatically when SIMH runs a PDP-11 OS.
- shoot a short .mpg to show an "idle pattern" of the console when it
  is not connected, running in "stand-alone mode".

Check www.pdp-11.nl and click the link [homebrew 'PDP-11'] at the left.

NOTE: I built this console with my PDP-11/35 as example. PDP-11's are
my focus of collecting ... The protocol used between the "front-end" and
the SIMH software is simple. I do not see any reason why you cannot hook
up a PDP-8 console or even any other blinkenlight console (e.g. HP-1000).
I real console (from eBay, I do not support the thought of stripping a
fine real machine just for the console ...!) could also be connected, it
is just a matter of wiring the switches and the toggles.

If there is sufficient interest, I *might* think of designing a lay-out
of a single board that contains the CPU and the I/O. Depends on how many
of you have interest in this project to keep the cost low. If somebody
works where he/she has easy access to a PC lay-out program and etch option
(double-sided PCB, with metalisation through the holes), I will gladly
assist and provide answers for any related question.

  kind regards,
- Henk, PA8PDP
Received on Tue Apr 13 2004 - 07:05:00 BST