Talk:PDP-6

Memory management

I am unable to find a reference that says definitively whether or not the PDP-6 had any memory-management hardware for support of time-sharing. It would have been, at most, a base/bounds register pair type arrangement, the same kind of thing the KA-10 had. My suspicion, from allusions in the ITS manual, is that it did not. However, until we know for sure, I'll leave the mention of such support in this article for now. Noel 17:10, 1 Sep 2003 (UTC)

An article I was looking at provided the details. It had a single base/bounds register pair, unlike the KA-10 which had two of them, allowing the Unix model of separate read-only code segment, and read-write data/stack segment. Will update the article. Noel 03:42, 13 Sep 2003 (UTC)

Also, the claim about support for batch was incorrect. The Bell book (cited) says explicitly that there was little/no support for batch. Noel 12:42, 13 Sep 2003 (UTC)

I was there (at Livermore which purchased an early PDP-6) and can confirm the above including details on the two relocation registers from DEC. Dave Pehrson at Livermore built a paged memory map for the PDP-6 for the [| Octopus project]. NormHardy 00:46, 22 October 2007 (UTC)

Errors in recent re-write

I removed the following:

BBN used their PDP-6 to develop the completely new TENEX operating system, which was later purchased by DEC and renamed TOPS-20.

because it's not correct (as far as I can ascertain). The long Origins and Development of TOPS-20 article by Dan Murphy points out that BBN didn't even buy a PDP-6 (which is confirmed by the list of PDP-6 serial numbers, see links added to the page), and various TENEX sources (the Murphy article, plus TENEX, A Paged Time Sharing System for the PDP-10) say that TENEX from the start used the KA-10, and the paging box built for the KA-10. Perhaps the now-deleted text above resulted from a confusion with ITS, where early versions were developed on the PDP-6?

Also, I haven't been able to find explicit documentation on the name of the OS used on the PDP-6; Bell, Mudge and McNamara has a table of its capabilities, compared to the OS's on the later PDP-10 processors (pp. 507), but gives no name. I doubt it was called TOPS-10, because that name came in with the (later) PDP-10. Perhaps TOPS-10 was a descendant of the PDP-6 code, but I suspect they were quite different - see the B/M/M table for all the differences (in addition to the different memory mapping capabilities of the PDP-6 and KA-10). Noel (talk) 03:58, 11 Jun 2005 (UTC)

Bell, Kotok, Hastings and Hill ("The Evolution of the DECsystem 10") says: "The Monitor was the name given to a collection of programs that were originally core-resident and provided overall coordination and control of the operating environment", and refers to the OS as "the PDP-6 Monitor" throughout. See http://research.microsoft.com/en-us/um/people/gbell/cgb%20files/evolution%20of%20decsystem%2010%20acm%207801%20c.pdf - it's a fascinating paper.

I do know that the name "TOPS-10" wasn't used until after the release of the KA10, but I'm not sure of the actual date. So I suppose that the PDP-6's OS was simply referred to as the Monitor. Kay Dekker (talk) 16:00, 5 February 2009 (UTC)

You are correct, the operating system software on the PDP-6 was called the Monitor, or sometimes the PDP-6 Monitor. John Sauter (talk) 04:35, 6 December 2009 (UTC)