8 Feb
2026
8 Feb
'26
7:19 a.m.
On Feb 7, 2026, at 3:57 PM, Donald Whittemore via
cctalk <cctalk(a)classiccmp.org> wrote:
My Dad was a 360 operator, as was I. I will swear he set the load unit as 00C and hit
load. In the card reader was something labeled CID. Compatibility Initialization Deck. Was
less than 1/2 inch of cards. I believe it put the Mod 30 (or 40) into pure 1401 mode. No
360 code running.
You can certainly IPL off the card reader, though I've never done it. I did see the
360 model 44 "emulator" deck, which is loaded that way using the "Emulator
IPL" button, into a separate block of memory invisible during normal execution.
It's vaguely like Alpha PALcode, I guess.
That deck was a standard IBM 360 object program file, with the channel program on the
first card loading all the pieces to the right places.
No idea what this CID was. It could be simply a "bare metal" ordinary 360
program, or a 360 program combined with helper microcode.
paul