In the mid 1970's I used an OS on DEC equipment (I believe PDP-11) that had a guest mode. If you weren't an authorised user you could login as guest mode where you supplied a name and if it didn't exist it was created with a password and if it did exist you entered your password and then had access to a BASIC 'environment' where you could create/compile/execute/save BASIC programs. In guest mode when you logged out for each file/program stored you had to confirm that you wanted to keep that file/program. I don't know the capabilities for an authorised user as I only ever used it in guest mode.

Does anyone have any information about this system please?

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    Here is a comprehensive list of PDP-11 operating systems. Do you recognise any of the names on that list? Commented Mar 6 at 11:44
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    Discounting some of the less likely options in that list, my uninformed guess at this stage is that it might be RSTS as it booted into BASIC and many of the OS programs were written in BASIC (technically, "BASIC-PLUS"). MTS is another possibility, although I think RSTS (or a variant) would have been more likely. I couldn't find any reference to a "guest" mode or login in either OS though. Commented Mar 6 at 12:26
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    @Noel. I didn't know the name of the os then so I won't recognise it now. That's the main reason for this question to try to identify its name.
    – hptsb
    Commented Mar 6 at 16:17
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    @Noel. It wasn't RSTS/RT11 as I used RSTS later and I knew it well. RSTS didn't have a guest mode and the login id was a number pair. Might have been RSX/TSX (when did they become available as this was about 1976-1978). Did these have a guest mode? It was this guest mode that is intriguing to me.
    – hptsb
    Commented Mar 6 at 16:26
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    RSX-11M had a "USER" account that was designed as a sandbox environment for learning how the OS worked. What might provide some context is where you remember using this system, was it at a university or a business? This feature does sound like the kind of thing that would be included in a university distribution, or at least a university might customise it to work like that, and the straight-into-BASIC mode sounds like it's not UN*X. This is all conjecture, unfortunately. Plus, it's possible that this feature might be undocumented in the operating manuals if it's a custom thing. Commented Mar 6 at 17:48


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