You can:
Select any of the 40 salts
Conduct tests (1-8) on any of the 40 salts
"GUESS" what it maybe
"STOP", in which case it'll advise what the salt is.
What seems to be missing is the "HELP" option to Help interpret the Tests.
The programmes usable, but incomplete because "Popular Computing Weekly" didn't publish the rest, or maybe the author only made that part available when sending a Blank Tape along with £2.50.