What's MUD mean? (PDP-11 related, not MUD... You know what I , mean!)

From: Tony Duell <ard_at_odin.phy.bris.ac.uk>
Date: Thu Nov 20 04:54:54 1997

On Wed, 19 Nov 1997, Daniel A. Seagraves wrote:

> There's a few slots up by the CPU labled MUD. I think I know what it

MUD = Modified Unibus Device

Also, SPC = Small Peripheral Controller

> means. But I want to make sure. Does it mean Modified Unibus Device?
> And does that mean DMA slot? And does that mean all the screwing with the
> backplane I did was unneccesary?

A MUD slot means that the memory address/data bus is wired on the A/B
connectors (which are not used on a true SPC slot). On an 11/34 the memory
bus is just the Unibus, but on something like an 11/44 there's a 22 bit
address bus for memory. The C-F connectors will carry the Unibus signals,
just like an SPC slot

I think all MUD slots do carry the DMA signals, but on the SPC part. You
do still have to cut the NPG jumper from CA1 to CB1 (I can't think of a
way to make a unibus slot where that's not that case that will work with
all unmodified cards).


Received on Thu Nov 20 1997 - 04:54:54 GMT

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