Overview of old unix versions which can be run on simulated (or real) pdp-11 computers.
The UNIX-HATERS Handbook, a review on https://athornton.dreamwidth.org/14272.html is also worth reading.

See also his ANCIENT COMPUTER MVSEVM on https://mvsevm.fsf.net/
If you want an account on one of these systems, please email Adam Thornton <athornton@gmail.com> and ask.
All systems are emulated, on Raspberry Pi and Linux.

1: Multics MR 12.6f (Honeywell 6800 DPS-8/M)
2: TOPS-20 7.1 (PDP-10 KL-10)
3: TOPS-10 7.03 (PDP-10 KA-10)
4: ITS (PDP-10 KA-10)
5: OpenVMS 7.3 (MicroVAX 3900)
6: Unix v7 (PDP-11/70)
7: Unix 2.11bsd (PDP-11/70)

Announced on the TUHS mailing list. https://www.tuhs.org/pipermail/tuhs/2019-August/018253.html