Starting and stopping ITS

Except on KL10, starting ITS goes like this:

1. Start DSKDMP.
   • On a KA10 this is most often done from paper tape, but magnetic tape is also possible.
   • On a KS10, use the BT console command to boot into DSKDMP.
2. DSKDMP will announce itself eponymously.
3. Select an ITS core image. Conventionally it should be @ ITS. Type F Altmode to see a file listing.
4. To load and run ITS, type the file name and enter. If the first file name is @ that can be omitted.
5. First DDT is entered. Here's a chance to debug ITS, set breakpoints, etc.
6. To start ITS running, type Altmode G.
7. The Salvager will check the disks and then ITS IN OPERATION is printed.

On the KL10, there is no DSKDMP. DDT is used to load a core image and start.

Stopping ITS goes like this:

1. Log in and run LOCK.
2. Type 5DOWN to have ITS shut down in 5 minutes. This is the minimum.
3. Type Y to confirm.
4. Type a message terminated by a ^C.
5. Type Q to exit LOCK.
6. When all users are logged out, ITS will shut down immediately regardless of the grace period.
7. When “YOU ARE NOW IN DDT” is printed, it's safe to power off.
8. Optionally you can restart ITS from DDT, or go back to DSKDMP by jumping to address 777700.

A transcript of starting ITS, logging in, and stopping. It has been edited for brevity.

DSKDMP
its
$G
SALVAGER.317
ITS 1649 IN OPERATION
ITS 1649 SYSTEM JOB USING THIS CONSOLE.
^Z
ITS.1649. DDT.1547.
TTY 0
You're all alone, Fair share = 99%
:lock
LOCK.156
_5down
DO YOU REALLY WANT THE SYSTEM TO GO DOWN?
Y
PLEASE ENTER A BRIEF MESSAGE TO USERS, ENDED BY ^C
Bye.
^C
ITS 1649 NOT IN OPERATION
SHUTDOWN COMPLETE
PI LEVEL 7 BUGDDT. TYPE <ALTMODE>P TO CONTINUE.
YOU ARE NOW IN DDT.