7 Jul
2004
7 Jul
'04
6:59 a.m.
Paul Koning wrote:
>>>> "Megan" == Megan <mbg(a)theworld.com> writes:
Megan> Typically, for the -11's, the first block (block 0) of the
Megan> device is loaded at address 0. The DEC bootblock standard
Megan> calls for the first word to be a 5 (reset) and the second to
Megan> be a branch to the rest of the code (so that locations 4/6 and
Megan> 10/12 at a minimum are free for non-existent memory and
Megan> illegal instruction traps).
That doesn't match what I learned (or what's in RSTS 10.1). The reset
in location 0 was an old convention. But when a real boot block
standard appeared, it said that 0 had to be a NOP, and 2 a branch to
the setup code. Also, there had to be a "Szeto ID area" just before
the branch target. As a special case, PRO boot devices must have a HALT
(0) in word 0 --
obviously the ROM boot transfers control to 2 and not 0 as on other
PDP11s.
Starting with V05.03 of RT-11 from 1985 (a few earlier versions
may also support the PRO hardware), I set up a BOOT image
for a PRO device driver by:
COPY/BOOT:DZ dev:RT11FB.SYS dev:
I then checked the boot code in block zero of dev: and found
NO differences at all (except for the code specific for "DZ").
There was a "NOP" in location zero followed by a "BR addr"
instruction. VECTORs 60, 64 and 100 were all zeros.
Somewhere (very buried, but might be found if it was essential),
I have a bootable RX50 floppy that I tested on a PRO350 about
5 years (probably longer) ago.
If there are any more questions, please ask.
Sincerely yours,
Jerome Fine
--
If you attempted to send a reply and the original e-mail
address has been discontinued due a high volume of junk
e-mail, then the semi-permanent e-mail address can be
obtained by replacing the four characters preceding the
'at' with the four digits of the current year.