Former Microsoft engineer Dave Plummer took a trip down memory lane this week by building a functioning PDP-11 minicomputer from parts found in a tub of hardware.

It's a fun watch, especially for anyone charged with maintaining these devices during their heyday. Unfortunately, Plummer did not place his creation in a period-appropriate case, and one might argue he cheated a bit by using a board containing a Linux computer to present boot devices.

Nonetheless, the build will undoubtedly bring back memories, both good and bad.

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[2]Youtube Video

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Plummer's build started with a backplane containing slots for a CPU card, a pair of 512 KB RAM cards, and the Linux card – [5]a QBone by the look of it. Also connected to the backplane were power, along with some halt and run switches.

The QBone is an interesting card and serves as an example of extending the original hardware rather than fully relying on emulation. The device can emulate components of the PDP-11 as parts fail or become difficult to obtain. In Plummer's case, he used it to provide a boot device for his bits-from-a-box PDP-11.

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Once connected and with a boot device mounted, Plummer was able to fire up the computer with its mighty megabyte of memory and interact with it as if back in the previous century.

[7]Microsoft whiz dishes the dirt on the Blue Screen Of Death's colorful past

[8]The port of the Windows 95 Start Menu was not all it seemed

[9]A cheeky intern nearly turned MS-DOS into NSFW-DOS

[10]Windows Format dialog waited decades for UI revamp that never came

The PDP-11 had a long life, with a production run spanning various guises from 1970 until the final model was introduced in 1990. It is arguably one of the most successful minicomputers ever produced, and it's likely that IT professionals of a certain vintage have encountered one during their careers.

For retro fans lacking Plummer's big box of bits, there are plenty of ways to inject a bit of PDP-11 goodness into your life. In 2018, we [11]noted the replica kit available from Obselence Guaranteed. Sure, it's a 6:10 scale version, but there can be few living rooms that wouldn't benefit from 1970s-era blinkenlights.

As for Plummer's build, he determined it to be a PDP-11/23 Plus with an M8189 CPU and QBUS backplane. This would place the device in the very early 1980s. ®

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[5] https://retrocmp.com/projects/qbone

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[7] https://www.theregister.com/2024/08/02/who_wrote_windows_bsod/

[8] https://www.theregister.com/2024/07/29/windows_start_menu_port/

[9] https://www.theregister.com/2024/04/08/ms_dos_easter_egg/

[10] https://www.theregister.com/2024/03/27/windows_format_dialog_temporary/

[11] https://www.theregister.com/2018/05/21/raspberry_pi_pdp_11_revival/

[12] https://whitepapers.theregister.com/