[cctalk] Re: VM/370 notes

[Paul Koning via cctalk]

> On Feb 7, 2026, at 3:57 PM, Donald Whittemore via cctalk 
> <cctalk@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