2 Jul
2004
2 Jul
'04
9:01 a.m.
Any ideas as to where can I get more details on the
various OSes boot
sequence on the PDP11?
Should have details like what disk block goes to which core address, how
to find/load/jump to the kernel..etc.
Typically, for the -11's, the first block (block 0) of the device is
loaded at address 0. The DEC bootblock standard calls for the first
word to be a 5 (reset) and the second to be a branch to the rest
of the code (so that locations 4/6 and 10/12 at a minimum are free
for non-existent memory and illegal instruction traps).
It is possible to write the primary boot block of a volume to
contain the code to boot an entirely different device.
For example, I have a machine which only knows how to boot from RX01/02,
but I have an RL02 as well. I have one RX01 disk which has the RL01/02
primary boot code in block 0. So, when I boot dx0, the primary boot comes
in off dx0, but the remainder of the boot process references dl0.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL,ST| email: mbg at world.std.com |
| Member of Technical Staff | megan at savaje.com |
| SavaJe Technologies, Inc. | (s/ at /@/) |
| 100 Apollo Drive | URL: http://world.std.com/~mbg/ |
| Chelmsford, MA 01824 | "pdp-11 programmer - some assembler |
| (978) 256 6521 (DEC '77-'98) | required." - mbg KB1FCA |
+--------------------------------+-------------------------------------+