[StopGlobalWhining]

...the first true multi-tasking machines.

The 360 was the first machine with a combination instruction set that included characters (eg MVC), packed decimal (eg ZAP), integer arithmetic (AR), and floating point arithmetic (AWR).

I think GE's GECOS was the first generally available multi-tasking (time-sharing) operating system, but on that point I may be mistaken. It might have been UNICOS (UNIVAC 1108).

[NCjim]

I should have said IBM's first true multi-tasking machines. And you are of course correct that they were also IBM's first general purpose computers.