PDP OS Boot Sequence: WAS Re: RK05/RL02 Boot Sequence

From: Megan <mbg_at_theworld.com>
Date: Fri Jul 2 16:01:51 2004

>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 /_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 |
+--------------------------------+-------------------------------------+
Received on Fri Jul 02 2004 - 16:01:51 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:36:49 BST