First pre-emptive multitasking desktop computer, even Windows and MacOS didn't have it. However many mainframe and workstations did.
Yeah, I should have worded it differently :-)
Any computer can do it with the right os, including the C64 and similar machines 
Not sure I would want to try multitasking on a C64 :-) I did have a Commodore 486 for awhile which I used as BBS system where I had to multitask under DOS.
It was possible used DesQView and QEMM and could have three BBS nodes running, although I used just two.
One was for local logon and the other was for live.
Was really robust compared to Windows 3.11 :-)
