[TUHS] demand paged 32V / Contacting Kelleman and/or Buroff

[TUHS] demand paged 32V / Contacting Kelleman and/or Buroff

[Paul Ruizendaal via TUHS]

I’m still researching John Reiser’s 32V with demand paging, copy-on-write and mmap.

Unfortunately, JFR does not have the bits or a listing for this version of 32V.

I’ve read the MSc theses of Leffler and Shannon with interest (https://www.tuhs.org/Archive/Documentation/Theses/). The thesis of Shannon has an interesting discussion of a demand paged version of his Harris/6 Unix (Chapter 5). It is based on the Tenex ideas, just as JFR mentioned for his version. The thesis of Leffler contains a gant chart that shows that the demand paged version was written in the first months of 1980 -- concurrently with or slightly after the 32V version.

I’ve also (superficially) read the papers on Tenex memory management. The design is closely tied to PDP-10 MMU that BBN designed for Tenex. Some of its data structuring is recognisable in Shannon’s version. One defining aspect is that the design for both is for a virtual address space that is smaller than the physical address space; on a 1980 VAX it was the reverse.

If 32V followed the same design ideas (a big if), it most likely limited processes to a capped address space (e.g. 2MB). It might also have contained an in-core flag/data vector with as many entries as there are pages frames in swap space. If true, these downsides may have been why it did not go on to become the root for SysVR1 or R2 paging.

The demand paging code for SysVR2 was written by Keith A. Kelleman and Steven J. Buroff, and in contemporary conference talks they were saying that they wanted to combine the best parts of demand-paged 32V and BSD. They may have some additional memories that could help with getting a better understanding of the final version of 32V.

Does anybody have contact details for these two gentlemen?

Re: [TUHS] demand paged 32V / Contacting Kelleman and/or Buroff

[Chet Ramey]

On 6/20/21 6:05 PM, Paul Ruizendaal via TUHS wrote:

> I’ve read the MSc theses of Leffler and Shannon with interest (https://www.tuhs.org/Archive/Documentation/Theses/). The thesis of Shannon has an interesting discussion of a demand paged version of his Harris/6 Unix (Chapter 5). It is based on the Tenex ideas, just as JFR mentioned for his version. The thesis of Leffler contains a gant chart that shows that the demand paged version was written in the first months of 1980 -- concurrently with or slightly after the 32V version.

Sam and Bill did their work at CWRU, which was getting to be a DEC shop at
the time, at least in the central computing center. When I got there a few
years later, we were running DEC-20s with TOPS-20, and we were doing some
kernel and EXEC customizations (we == Case, I was not involved). It's
likely that both of them, and Rob Gingell, were influenced by exposure to
Tenex and TOPS-20. Rob would know more.

Chet

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/