Links to documents describing transputers and the Helios operating system, which has a GPL v3 licensed NG variant, https://github.com/axelmuhr/Helios-NG which appears to be dormant.
Mentioned on the TUHS mailing list https://www.tuhs.org/pipermail/tuhs/2024-September/030872.html
Some interesting documents are
There Is No Royal Road to Programs - A Trilogy on Raster Ellipses and Programming Methodology (M. Douglas McIlroy)
MM 67-4734-7 1967-05-15 2.54 MB An Introduction to the Available Programs and Other Design Aids for the Design of Filters, Equalizers and Other Networks
MM 67-5311-18 1967-08-29 1.27 MB Notes on the Design of Cosine Roll-Off Filters
A DECstation emulator on a business-card sized PCB. The description is a nice read. https://hackaday.io/project/196769-decstation2040 for a RP2040 version, with 32 MB HyperRAM, 1024 x 864 mono video, and USB mouse/kb