Test Monitor O/S, DEC XXDP clone. Operating system for running other tests, even in a "chain" (apparently it is a batch)
Versions V2 and V2.1 have survived, there is apparently also version 3.
There are different variants:
cpu set 11/40 att tm0 tmos2.tap # rx0 for 8SD floppies, ry0 for 8DD floppies, rk0 for IZOT SM 5400 boot tm0 # according to the relevant media