More on PDP 11/24 (hints & Maintenance Card infos needed)

From: Pierre Gebhardt <>
Date: Mon Jan 3 09:23:53 2005

Thanks alot for your advices and the links, Ethan.

> No. There are 1MB boards for the 11/24, but they are somewhat odd,
> IIRC. I have an 11/24 at home with a KT24 (M7134?) Physical Address
> eXtension (PAX) board that lets you put more than 256K of memory in
> the 11/24, giving it a slight edge over the 11/34, at least in terms
> of max memory (the 11/34C might be able to crunch numbers a bit
> faster).
> I reasonably confident that the 11/24 and 11/44 used the same memory.
> For 256K boards, it should be the M8722 (MS11-MB). Grubbing around on
> seems to suggest that the 1MB version is the M8743 (MS11-PB), but I
> don't have my hardware close at hand to check my own machines. Max is
> 4MB (as with any 22-bit address bus).

My 11/24 _uses_ the KT24 Mapping Module with the suggested MS11-PB, giving it 1MB of ECC Memory.
I can guarantee, that this combination works :^)
There's another board, I own: a MS11-LB (M7891-BB) with 128kb.
But I suppose that it doesn't make much sense to put this one together with the MS11-PB. The Ms11-PB is certainly
much faster than the MS11-LB.
Unfortuantely, the National Semiconductor boards can't be used, they were built for a VAX 11/750...

Currently, I have some problems to get this baby work.

There is a strange malfunction: When typing in some letters or digits on the keyboard (VT420), the screen turns
out some sort of random characters at the _at_-pormpt.
It's very weird !
Sometimes, when I turn it off and on to give it another try, it becomes impossible to type something.
The prompt is waiting, the cursor's blinking and the machine try to bootstrap, when pushing the boot-button,
but I simply can't type in anything !
The grant und bus connections are closed. The terminal works perfectly on local mode.

The "Clock" LED is on, in fact, never turns off, while the 1-LED (the one next to the Clock-LED) turns on when the PROM
for the CPU diagnostic is loaded (_at_165004g).
After that, both LEDs remain on.

The Maintenance Card for the 11/24 isn't on the internet (at least, I didn't find it), and there, the LEDs functions are described.
Could anybody give me some help on this ?

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Received on Mon Jan 03 2005 - 09:23:53 GMT

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