30 Apr
2015
30 Apr
'15
5:26 p.m.
On 2015-04-30 21:18, Don North wrote:
On 4/30/2015 9:55 AM, Johnny Billquist wrote:
Hm.. I could have sworn they were the same. Oh well. Figures. :-)
The per-device code are in separate PROMs that
are used in both the
9301 and 9312. Those are the ones with the device code as constants in
the beginning of memory space for the PROM, by the way. (I seem to
remember someone mentioning this in the past.)
Johnny
The M9312 device boot proms are totally different format and structure
than the M9301 proms. Not interchangeable. 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.
I thought I remembered moving boot roms from an M9301 to an M9312, but
that must be my memory playing tricks with me then.
The 11/44 module has its own console boot code PROM,
but it uses the
standard M9312 device boot PROMs.
Yes. As do the 11/84 and 11/94, which can take those boot roms in the
Unibus adapter.
For the M9312, there are two console PROM variations,
one for the
11/04/34/etc class machines, and one for the 11/60/70.
Right.
Johnny