[TUHS] CSR in V6

Noel Chiappa jnc at mercury.lcs.mit.edu
Sun Feb 27 17:38:12 AEST 2022

    > From: Will Senn

    > My question is - how did y'all run things - with CSR zero and no kernel
    > messages ... or with CSR non-zero and kernel messages.

On the -11/45 V6+ at MIT, we didn't have a printing terminal on the console,
just a VT52. We had a tool at MIT called 'dmesg':


which made up for that a bit.

We normally ran with the CSR set to 173030 - the 'boot in single-user'
setting. That's because at one point the machine was in the 9th floor machine
room, but the console VT52 was on the 5th floor (where our offices were - the
famous print of the GE-645 Multics was on the hallway wall outside mine :-),
and I'd added a 'reboot()' system call (nothing fancy, it just jumped to the
bootstrap ROM), so we could reboot the machine without going up in the
elevator (not if it had crashed, of course). Later on, after we'd done with
kernel hacking (adding a network interface, and IP), and the machine stayed up
for long periods, we moved the console up next to the machine (since if it
crashed, you had to use the front panel to restart it, so you had to be up
there anyway); we stayed with the default CSR setting, though. (If it panic'd,
you could see the reason why when you went to reboot it.)

    > Oh, BTW, I know I've seen this noted elsewhere, but I can't remember
    > where.

Maybe at:


which discusses it?


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