How much RAM is 64K 36bit words of Core Memory 790

It didn't even have load register. The20 was an interesting attempt at a low-cost low-end machine for the accounting machine crowd. The instruction set was an almost compatible subset of the 360, other than the I-O, and if you were careful, you could write buttembler code that would run either on a20 or a real 360 so long as it made library calls to do the I-O which was different.

At Princeton they had a bunch of20s used as RJE terminals to the 360-91 mainframe. It was a good choice, since the20 had a fast card reader and punch (the infamous multifunction card machine which could read, punch, interpret, and-or sort each card), a high end 1403 printer and a bisync modem.

When the91 was down, which was often, it was an awful lot of fun to program from the switches. The20 IPL read a card image into a fixed place and started it, so we had a contest for the most interesting program that would fit on one card, hand keypunched of course. Mine was expensive mimeo machine which would read a deck of cards and print it over and over with a page skip between copies.

R's, John