1 Mar
2018
1 Mar
'18
11:43 a.m.
Noel;
Thanks for the exact info I was looking for!? I knew there was a text
listing of the addresses and what devices occupied those addresses.?
Going thru the manuals one by one was way too tedious.? Thanks for
explaining the 'bank switching' that is done to accommodate the larger
boot roms.? Suspected that was going on but didn't really know.
I'm curious because I have an MXV11-AC without the boot rom, however it
does have another OEM rom there that I could reprogram with the standard
bootstrap.? This led to the question I posted.
Doug
On 3/1/2018 7:00 AM, Noel Chiappa via cctalk wrote:
From: Douglas
Taylor
Is there a document that describes the bank 7
memory page and what
addresses are reserved for what?
Here's one I collated from a large number of DEC manuals:
http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/UNIBUS_Registers.txt
(Ignore the name, it applies to QBUS machines too.)
bootstrap is reserved for 173000, how many words
are allowed there for
this?
Well, the space from 773000-773776 (UNIBUS and Q18 - add '17' to the front
for Q22) is used for ROMs, and is the most common; 173000 is of course the
location QBUS processors can be configured to jump to on power on. 765000-776
in also used for some (e.g. M9301's).
How do the more complicated bootstraps, e.g.
microPDP11-53, accommodate
this limitation?
Bank switching; e.g. the BDV11, KDF11-B have a 'page control register' at
777520 which says which block of ROM is mapped into the 773000 block.
Interestingly, the DEC standard ROMs for the BDV11 and KDF11-B _don't_ copy
all the contents down to real memory, and run from there - the code is
divided into 'pages', only one of which is mapped in at a time, and it's
executed from the ROM.
Noel