M9301-YB Bootstrap/Terminator ROM dumps / listings?

tony duell ard at p850ug1.demon.co.uk
Thu Apr 30 23:31:55 CDT 2015

> Hm.. I could have sworn they were the same. Oh well. Figures. :-)
> > The M9301 has four 4b wide proms configured as a 512x16 and the console
> > and device boot code all live in this address space.
> That is also true of the M9301.
> > The M9312 (and the 11/44 also) have one 4b console PROM, and four slots
> > for 4b wide device boot PROMs. Each of the PROMs are nibble accessed to
> > build a 16b word from four 4b nibbles. The PROMs are all independent of
> > one another.
> Yes. And this is more or less also how it works on the M9301. However,
> it seems that DEC didn't actually put difference devices in their own
> roms for the M9301, but treated the whole ROM memory as a big chunk with
> a bunch of different devices bootstraps in there.

It's been many years since I looked at the printsets, but I thought the M9301
had 4 off 4-bit wide PROMs that were read out together to make a 16 bit
word, and that therefore all 4 PROMs have to be present. The M9312 uses
hardware to read a 16 bit word out of 4 locations in a single 4 bit wide PROM,
so the 4 PROMs on that card are independant of each other, each normally
contains the bootstrap for a particular device.


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