Oscar Vermeulen made a cute PDP-8/I replica. People love it, the web is full of images and stories.

Offical web presence is here: http://obsolescence.wix.com/obsolescence#!pidp-8/cbie

It's called "PiDP8" because a RaspberryPi is build in.

See it here together with a REAL PDP-8/I and a monitor with the Java panel simulation:

Three PDP8I's: DEC original, BlinkenBone Java simulation, PiDP8

Choose your '8/I ! (click to enlarge)


Use the PiDP8 with REALCONS SimH

On GitHub there is a "rpi" distribution. This contains all binaries to run on the RaspberryPi, among others the special BlinkenLight API server for the PiDP8.

Quick start:

  1. Make an network connection to the RPi,
  2. copy the panelsim_rpi.tgz over,
  3. login with ssh and unzip with "tar xzf panelsim_rpi.tgz". It will need 1.3 GB, since all simulated machines with their disk images are installed !
  4. execute ./pidp8.sh

Then ADVENTURE is started on OS/8, the lights on the PiDP8 begin to blink. Now SimH can be operated over the PiDP8 replica switches.

If you execute ./pdp8i.sh instead of ./pidp8.sh, you start the Java panel simulation. You need to connect a monitor on the HDMI port then.


Tired of ADVENT?

Everything written for the simulated PDP8 Java panel applies to the PiDP8. See here how to build and toggle-in own assembler programs.


Why a 2nd SimH implementation for the PiDP8 ?

Why not ?

The PiDP8 comes ready-to-use with a modified SimH, so connecting to BlinkenBone is really not necessary.  But I liked to play with it! As test case for later projects I made an Blinkenlight API server for the PiDP8, so it's now part of the BlinkenBone world.

You can easily switch from the Java PDP-8/I simulation to the PiDP8 as front end, without leaving the BlinkenBone environment.

If you connected on your desktop to the Java panel with

sim> set realcons host=localhost panel=PDP8I connect

then switch to the Rpi (after starting rpcbind and the server there!) with:

sim> set realcons host=raspberrypi panel=PiDP8 connect

The PiDP8 server contains a anti-flicker low-pass and simulates slow lightbulb with the LEDs.


That "Deposit" switch again

As on all DEC panels, the "Deposit" switch has a reverse polarity, to prevent accidental memory change.

For the PiDP8 replica only bi-stable switches could be found (and that was hard enough!), so the mechanical "Off" position must be set by hand.

Compare with the physical PDP-8/I panel:

blinkenbone pdp8i deposit blinkenbone pidp8 deposit

The default SimH of Oscar doesn't implement the Deposit as inverted. So Oscar's SimH and my PiDP8 server behave different here.