PDP-11: Programming like it's 1975

In April of 2023 I acquired the popular PiDP-11 kit from Oscar here. It is currently my favorite machine to program for. Here's a picture of me running a sample program for the first time.

Programming the Hard Way

I wanted to immediately start programming, so I started by entering sample programs I found online into memory using the switches located on the front of the unit. This is not an ideal long term solution, but it has taught me a lot so far.

To start messing with memory after boot up, do the following:

• Boot into the sample blinking lights program
• Move the "ENABLE/HALT" switch down to halt the current program
• Depress the "LOAD ADRS" switch to load address 000000₈
• Start entering opcodes and data

This is the short and simple version of events. I will explain more as we go.

Resources

Here are some good resources I have found:

• Book: "Introduction to the PDP-11 and its Assembly Language" by Thomas S. Frank
• Website: bitsavers.org's DEC manuals archive
• YouTube: DEC's "Introduction to the PDP-11" tape series archive
• YouTube: Douglas Harm's "Programming the PDP-11" video series

Source code for all of my PDP-11 programs can be found on this GitHub page.