27 Dec
2015
27 Dec
'15
2:34 a.m.
On 12/26/15 1:26 PM, Ronald Natalie wrote:
Note that all this “boot loading” stuff was only
necessary if you didn’t already have a boot rom board (the common one for the early PDPs
had a bunch of diodes you clipped). Ours was set to boot RK Drive 0 so even after we got
a larger drive (80MB seemed like an infinite amount of storage after dealing with 2.4M) we
left a disk with the bootstrap in RK0.
I can’t remember the boot address on that machine, but the boot for the 11/70 I used for
years at BRL is still ingrained in my memory: 7765000 (while it isn’t exactly right, I
used the Glenn Miller PENNSYLVANIA-6-5000 as a memory aid). Long after we gave up using
PDP-11’s for UNIX machines, I recycled them all into internet routers using my own
(“Little Operating System” LOS). We had started with Noel’s MIT gateway but he was
exiled at the time to the Bahamas or something and we decided it was easier starting over
with the magnitude of changes we needed to make.
Thanks for the reply. SimH has built in boot ROM code for the RK
controller and other devices as well. So, the boot loader code isn't
really necessary, but I like to understand the things I am reading and
the boot loader code is presented in the set up instructions, so I
wanted to understand them before I moved on to other areas.
I appreciate the historical perspective. Glenn Miller, that's fun.
Regards,
Will