Compiling and Installing
pidp8i-test is a simple program to test Oscar Vermeulen's PiDP-8/I
Kit during construction. It is built and installed alongside
the other software with the normal
If you're running one of the binary OS images, simply give these commands:
$ pidp8i stop $ pidp8i-test
The first command ensures that the modified PDP-8 simulator is stopped during the test, since only one program can be talking to the switch and LED array at a given time. (This also applies to other programs like Deeper Thought 2.)
If you built the PiDP-8/I software from source atop some other Raspberry
Pi operating system installation, you will have to log out and back in
after installing the software so the installer's adjustments to your
PATH take effect. Then you can use the commands above.
The test normally proceeds automatically forward, but you can take control of the test sequence with these keys:
|↑ or →||Skip to next test|
|↓ or ←||Go back to previous test|
|R||Resume auto-advance behavior|
|X or Ctrl-C||Exit program|
Any of the arrow keypresses stop the auto-advancing behavior.
The test proceeds as follows:
All On test:
It turns on all LEDs for 5 seconds.
All Off test:
It turns off all LEDs for 5 seconds.
It turns on one full row of LEDs and pauses for 5 seconds, then switches to the next row. There are eight rows of LEDs of up to 12 LEDs each.
It then turns on one full column of LEDs and pauses for 5 seconds, then switches to the next column. There are 12 columns of LEDs with up to 8 LEDs each. (Some of the LEDs positions in a column are sometimes rather chaotic, it will require intimate knowledge of the schematic to verify. It's somewhat of a useless test but it might turn up an assembly error for someone.)
It then goes into a single LED chase pattern and starts looking at switches. This loop is infinite. Every time it detects a change in the switch positions it prints out the full Octal bit pattern for the three switch banks. No attempt is made to name the actual switch that has been flipped. The goal is to verify switch functionality, not to debug the design of the circuit or the driver.
When running this test, if you get a new line printed with a single bit change when you flip a single switch, the switch in question is working. If you get no output printed or multiple bits changed in the output printed something is wrong.
If for some reason you need to decode the output bits to physical switches they appear as follows:
A B C 4000 0000 0000
The first twelve bits (labelled A) is the Switch Register. The bits left to right correspond to the SR switches also left to right. So above the SR1 switch is toggled down, ie 1. Every other SR switch is up, ie 0.
The leftmost 6 bits (labelled B) are the 3 DF switches followed by the 3 IF switches. Again left to right. The rest of the bits are unused in the B section.
The leftmost 8 bits (labelled C) are the remaining 8 switches starting at "START" and ending at "SING INST". Again Left to right.
This document is licensed under the same terms as the associated