A 1980s PDP-11 is still running Unix – and now you can watch

Fresh from releasing TMOG, his take on a cross-platform Task Manager upgrade, former Microsoft engineer Dave Plummer has put his PDP-11 on the web.

The PDP-11 is a family of minicomputers from Digital Equipment Corporation that became a fixture of computing labs and early Unix history. Plummer's machine is real 1980s hardware, still running a Unix-derived operating system.

The website displays the machine's running processes, refreshing the list every few seconds. Think Task Manager for an old Unix box: ps lists what is running, while top keeps that view up to date. Visitors can't issue commands themselves, but they can watch the hardware at work.

REG AD

Plummer explained: "My love for all things Task Manager was born when I was a kid in the 80s, tinkering with the PDP-11/40 at the local university. Ever since I was a kid I was fascinated with multiuser systems, playing with ps and top to get a sense of the machine and what was happening on it.

REG AD

"And since 'top' is where it all started for me, when I came full circle with TMOG, I wanted a tie-in back to my old PDP-11. Ps is the simple process list. Top is an automatically refreshing screen of that process list and a few other stats thrown together."

A few years ago, Plummer tried to get an AI to write a version of top for 2.11BSD, the operating system running on his machine. At the time, he said, "it wasn't yet ready or able."

"Today it was, and it cranked out a top implementation for me quickly in C, about 400 lines of code."

The site refreshes the process list every five seconds, with a cache between visitors and the PDP-11 to limit the demands on the machine.

We'd categorize this under "cool" and "a little bit pointless", which all the best projects are. Plenty of PDP-11 emulators are out there, and many run in a browser, but there is a certain delight in seeing output from actual hardware.

Plummer's machine is a PDP-11/83 with several upgrades, including a Mentec M11 CPU complex and a mighty four megabytes of RAM. It also has old disks, magnetic tapes, and serial terminals to delight fans of the era.

There's something hypnotic about watching the process list, enhanced by the amber hue, and Plummer's enthusiasm for the retro kit is undeniable.

"Among the processes you'll see running, inetd is the internet server. It launches things like ftpd and httpd to 'run the web'. You can see sendmail also running to handle email."

REG AD

"They all work in concert to bring an internet presence to life from 1984!" ®