[geeks] Emulation versus replication

[CareySchug at aol.com]

Nits first: I don't think there was a device that would read cards, punch 
cards and print on them except the MFCM (multi function card machine) which at 
least for most of its life only connected to the 360/20, which was not a real 
360 (limited instruction set, no supervisor/user states or memory protection).  
There was a 1404 printer that would read up to 20(?) columns on each of two 
cards simultaneously, then print on them...or it could print on normal pinfeed 
paper instead.

You left out VM/BSEPP and VM/SEPP.

I have one of the mylar micro code cards for the 360/30 (somewhere).  They 
were called CCROS (card capacitive read only storage), although they were 
actually used in pairs.  An IBM SE could punch out a card per instructions (or copy 
the old card and change a column or two) to "fix" a microprogram bug.

The most common card-read-punch was the 2540, it would read cards on one side 
and punch them on the other, and could mix the cards into the center pocket.  
There was also a 2520 punch.  I think the 1402 card read punch was from the 
1401 computer, and not useable on the 360.  There may have been another 14xx 
card read punch, but I don't think it was 140x.  Hmmm, I think there was a 1442 
card machine and a 1443 printer.

Xedit came from Edgar, which I think is still available to run on vm release 
6, which is also available (I have the original round tapes, as well as 
emulated tape files on a PC).  What will really hurt about going back to vmrel6 will 
be the lack of REXX and was there even exec-2 prior to SP?  I don't remember 
on that one.

FWIW, I have some of the old rectangular metal signs from old 360s, so I 
could past one on my PC....


In a message dated 9/9/2003 6:07:48 AM Central Standard Time, 
gsm at mendelson.com writes:

> The last hard [wired] IBM mainframe, the IBM 1401 series (1960-1963) could
> be emulated by loading a card deck into the 360/30. It then became a
> real 1401 and temporarily lost its 360 identity. Later versions of the
> emulator ran under operating systems and my last brush with a 1401
> emulator was in 1979 on a 370/168 running MVS.

The emulation was in microcode.  The card deck or program just set it.  You 
could also jump to emulation mode with a diagnose instruction, so some of those 
user mods you talked about (back then the DOS and OS nucleus was open source 
too) let people run a program in any user partition to temporarily run 1401 
emulation, while still under control of the DOS/360 scheduler etc, long before 
the 370 and before VS1, VS2, SVS or MVS.  There was another card deck you could 
IPL (on a 360/30) that would let you run TWO emulated 1401s using just the 
buttons and dials on the console.