OS/8 (1971) for PDP-8, installed in SIMH emulator.
Download link (254 kb)
How to start OS/8
You need to start an emulator from this archive (pdp8.exe) and type:
For list of commands type:
Attention: only uppercase commands are allowed.
MAKE FILENAME command is interpreted as a command to start TECO and create the named filename. TECO (Text Editor and COrrector) was the most popular editor before VI and Emacs. Emacs originally stood for Editing MACroS running on TECO.
If you type MAKE LOVE, TECO will answer:
This joke is implemented in most command languages of the DEC company.