Raspberry Pi Powered PDP-11
Written by Harry Fairhead   
Sunday, 25 April 2021

My attention was attracted this week to a vintage computer kit building experience. Retro Viator gave his account of the PiDP-11/70 from Obsolescence Guaranteed, which is a small-scale replica of Dec's PDP-11/70, a landmark mini computer of the 1970s.


According to  Retro Viator:

The PDP-11 was DEC’s first 16-bit computer, and cost $20,000 when released in 1970. Reportedly, 600,000 units were sold over its long life, and it was the tool of choice for countless computing innovations, including the creation of UNIX and the C programming language.

This PDP-11 project takes me straight back to my days as a PhD candidate at University College London while at the same time chiming with my current absorption with the Rapsberry Pi family. 

Remember the 1970s, it was my job as the Department's junior member  to key-in the PDP-11 load sequence every morning.

You see the piano-style keys numbererd 0 t0 31 to the left of the white spacer key grouped in threes. They were used to  input the sequence in Octal. I did it so often I'd memorized the sequence and could input it in around 20 minutes after which I'd load the paper tape. While the start up sequence completed there was time for a coffee - now that's a bad memory 1970's instant coffee - before being able to get on with my project - except that almost inevitably my room mate would have arrived in the interim and taken over the machine we shared with two others. Luckily I was allowed to have the most access to it as I was charged with writing the operating software for the state-of-the-art image processing software that was vital for the entire department's ongoing research projects. Ah those were the days. Perhaps not and imagine what we could have done given today's hardware.

Back to the 21st century and the Raspberry Pi which is used to run the PDP-11 emulator. Well it doesn't cost $20,000 for a start. The top-of-the-range Raspberry Pi 4B with 8GB RAM will set you back around $90 or if you opt for a kit  including case and 128GB Micro SD card $149.99, see side panel. These would be overkill for this project and Retro Viator used a Model 3B for less than $40. 


The kit from Oscar Vermeulen of Obsolescence Guaranteed for the PDP-11/70 is first rate, as are the accompanying videos which provide help for novice builders. You can read more about them in my report Experience the PDP-11/70 With Raspberry Pi.


There's also a kit for the PDP-8/1, see  PiDP - A Pi Based PDP-8/I.

More Information

PiDP-11: Recreating the PDP-11/70

PiDP-11: Retro Viator

Related Articles

Experience the PDP-11/70 With Raspberry Pi

PiDP - A Pi Based PDP-8/I

Gordon Bell And DEC - The Mini Computer Era 

Raspberry Pi and the IoT in C - I2C Temperature Measurement


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Last Updated ( Sunday, 25 April 2021 )