MUD MEM UBA SPC et al

[iainmaoileoin]

I am looking for a reference to a page or 10, to save me googling for hours.

Now that I am happy my '73 does what I want,. I am about to start on 1 of my '84s.

It powers up and runs, but the peripheral cards include DT07 and thing like that that I want to pull and replace with things of more interest to me - like tK50s ;-)

Anyway where can I get a summary of the various unibus names/terms that are used on the '84 backplane (KA90101940) perhaps 73 35190-01-REV A1 ML.


Some photots of the beast are here http://www.scotnet.co.uk/iain/DEC/11-84-2/index.html.

Specifically does anyone know if I can put an AB qbus card into MEM slot 3?

Any clues/links appreciated. I should have listened more to the lectures in 1975 about the unibus.

 

[iainmaoileoin]

Stolen from another web-page:
Tne system units usually provides place for 4 x 6 (4 rows, i.e. 4 x A-B-C-D-E-F) or 9 x 6 (9 rows, i.e. 9 x A-B-C-D-E-F) slots. The system units are connected to each other with jumper modules. The system units can be wired differently. There are two main sorts of "non-trivial" slots in a system unit:

SPC (Small Peripheral Controller) slot:
In this case, the module to be inserted is a quad-height board, using slots C-F. Later SPC cards are really quad-height, early SPC devices consisted of several cards: the dual-height controller in C-D, an M105 address selector module in E and an M782 (or M7820, or M7821) interrupt control module in F. A and B remain unused.
MUD (Modified Unibus Device):
A MUD slot has non-Unibus signals (and power) on slots A-B, e.g. this two slots can be part of the memory bus, or a local interconnect.

Questions: If the backplane is HEX but an SPC is QUAD (C-F) why have A+B?. Am I correct in saying that you cant put a hex card in a SPC slot - only a unibus quad-height board?

 

[AK6DN]

All UNIBUS backplanes are hex. Sections C-D-E-F are always SPC pinout, in every slot. A-B are UNIBUS in the first and last slots. A-B are MUD in the 2nd thru N-1st slots. This is for UNIBUS-only backplanes like the 9 slot DD11-DK and the 4 slot DD11-CK.

There are other variations of backplanes that have dedicated slot assignments (eg, like the DD11-PK 9 slot that has the first two slots wired for the 11/34 card set). The 11/44 backplane is similar, it has lots of dedicated slots for specific processor boards, but does have a number of MUD/SPC pinned slots.

The confusion is because you assume an SPC is a slot, but in reality it is the pin assignment in positions C-D-E-F of a slot. There are both HEX and QUAD I/O cards that are SPC pinout. QUAD SPC cards can go in any UNIBUS SPC slot, as they only occupy sections C-D-E-F. HEX SPC cards can only go in the 'inner' (not first or last) slots of a UNIBUS backplane. Sections A-B of those slots are pure UNIBUS, and need to be occupied by UNIBUS cabling, backplane-backplane jumpers, or a UNIBUS terminator card.

All MUD interfaced UNIBUS boards are (usually) HEX boards, and are just memory cards (as the MUD section does not have the BR/NPR in/out signals per slot). There is one dual A-B MUD card I know of (the M7850 parity controller) but it is usually only used in core memory configurations and is not very common.

An M7856 DL11-W is a very common QUAD SPC card. The M7762 RL11 controller is an example of a common HEX SPC card.

Don

 

[iainmaoileoin]

Thanks, Don - very useful that condenses a lot into a little.

I am working on an 11/84 with a 9 slot (1x cpu 2x mem 1x uba) then a bunch of unibusses.

I have many more qbus than unibus cards (disk controllers etc) and cant phathom if I can fit a qbus into an "unused" mem slot on the 11/84 (I have an M7556 load card in that unused slot).

H/W wise I can think the singals are seriously wrong, I can also imagine that the UBA wont "see" the card in the MEM slot and thus wont clear cache if/when the card is accessed. I dont have the energy to work out if DMA requests from a disk contoller would actually make it to memory! Any comments apart from RTFM?

The only card that I have in a MUD slots is a hex DT07 (8721) card.
I do have a hex RL02 disk controller in a "standard" SPC.