Talk:PDP-10

Category

The reason I put this page in Category: DEC Systems was that it covers a number of different machines; KA, KI, etc. So it's not really a PDP-10 system, but it covers them all. But I can see the point of putting it in Category: PDP-10 Systems, and since that cat goes in 'DEC Systems', it's still findable, so it's OK there too. Jnc (talk) 15:22, 5 July 2019 (CEST)

PDP-10 emulators

There is a bit of a difference between the functionality of the PDP-10/X and PCjs's PDP-10, much larger than hardware vs Software.

David Conroy's, advanced beyond the PDP-10s architecture, ran faster, and could use IDE disks, and with a software modification run ITS on a disk larger than 32MB, ( and ran on a 500MB disk ), as well as a full DEC Net protical layer, which allowed him to clone disk installations over networking.

He had some problems emulating the Floating point instructions, specifically mentioning FDIV

PCjs is "WARNING: PDP-10 emulation is still in development, so functionality will be limited until further notice."

It gives this funny init warning. "PCjs Machine "testka10"

ForOldHack (talk) 03:38, 25 January 2021‎

PDP-10 Buses

I'm toying with the idea of moving the PDP-10 bus material to a separate article. Actually, maybe two separate ones: PDP-10 memory buses, and PDP-10 I/O bus? What do people think? Jnc (talk) 18:56, 25 September 2022 (CEST)

Are you planning on expanding the text? If so, sure, separate pages would make sense. If no, I don't think the current text bloats the article much. Larsbrinkhoff (talk) 22:02, 26 September 2022 (CEST)

Ah, sorry; I should have explained what the motivation was. It would not be size; it would be to make it easier for other articles which wish to link to detailed content on various PDP-10 buses to do so. At the moment they have to link to PDP-10#Busses, which is not very clean. One or two, OK; but there are lots of pages that want to link to PDP-10 buses. Jnc (talk) 01:05, 27 September 2022 (CEST)

Yes, I know it's not the most iron-clad case (as the expression in English goes), because one could just use a 'section link' (as above), but I think the two things are important enough to warrant the existence of PDP-10 I/O Bus and PDP-10 Memory Bus as top-level articles. Jnc (talk) 12:50, 21 October 2022 (CEST)

Well ok, if you think they are important, sure why not? Now that I have a READ IN switch to play with, I think it would be interesting to describe hardware read-in in detail. Larsbrinkhoff (talk) 13:41, 21 October 2022 (CEST)

KL20?

The CACM paper "The Evolution of the DECsystem 10" contains the following interesting sentence:

The cost-reduced KL20 evolved by integrating the Massbus controllers and PDP-11 interfaces onto a single high-speed, synchronous bus.

but I've never heard of a KL20, or any system that could be described that way (below). OTOH, two of the authors (C. G. Bell, A. Kotok, T. N. Hastings, and R. Hill) were in a position to know authoritatively. Perhaps one of the other two added this erroneously, and the two main authors didn't catch it? Or perhaps this is a reference to a later-cancelled machine?

The 'KL20' can't be the KS10, as that has no PDP-11's, and its Massbus controllers are on a UNIBUS. (Although the main memory bus might be synchronous, I don't recall the details). Equally, it probably can't be the later TOPS-20 KL10 machines (such as the 2060); although they look quite different, and have only an internal memory bus, other than that they are internally basically identical to the earliest KL10's, and also can't really be described as a "cost-reduced" machine. Jnc (talk) 12:24, 27 October 2022 (CEST)

I checked the paper, and the most likely explanation I can see is that what it refers to as "KL20" really is the KS10. The paper is from 1978, just about when the KS10 went to market, so presumably the name may have been in flux. Under this theory, the phrase "integrating the ... PDP-11 interfaces onto a single ... bus" would refer to the KS10 having Unibus rather than the legacy PDP-10 buses. Note that it does not really say the KL20 has a PDP-11, just the interfaces of a PDP-11. No, the Massbus isn't integrated, so that's a point against. Note also the list of five implementations: "PDP-6, KA-10, KI-10, KL10 and KL20", where the KL20 sits exactly where you would expect the KS10. It certainly fits the theory that the KS10 is massively cost-reduced over a KL10. Larsbrinkhoff (talk) 13:31, 27 October 2022 (CEST)

Very good point that it doesn't say 'PDP-11s', but "PDP-11 interfaces". And maybe the "integrating the Massbus controllers and PDP-11 interfaces" refers to the fact that they all talk to the KS10 memory through a UNIBUS interfaced to the memory.

So maybe it really is the KS10; that certainly is cost-reduced over the KL10.

If I get a chance, I'll read the KS10 tech manual and see if its main memory bus is synchronous. Jnc (talk) 14:27, 27 October 2022 (CEST)