There was the operating systems CMS
and CP67 done by the IBM Cambridge
Scientific Center for the IBM 360/67
in, right, about 1967. The CP67
was
control program 67 and was for
virtual machine. CMS was Cambridge
Monitor Systems, maybe off and on
Conversational Monitor System, and
the command-line time-sharing operating
system users saw.
CP67 was intended as a means for
interactive, time-shared operating system
development. So, right, could run
CP67 on CP67 -- once that was done
7 levels deep.
The combination CP67/CMS was, for the time,
a total dream for a time sharing system.
Stop malicious code? Sure: On CP67
write and run any code, any instructions
doing anything you want with any data you
want, and you just cannot bother
any other users. So, could run malicious
code safely.
I used CP67/CMS and PL/I from National CSS
Time Sharing in Stamford, CT to schedule
the fleet at FedEx. Founder, COB, CEO
Fred Smith's remark about the output was
"Amazing document" "Solved the most important
problem facing FedEx". The Board was pleased
and a nice chunk of funding was enabled.
It literally saved the company. No,
Fred never gave me my promised stock,
that once he said would be worth
$500,000. Add a few zeros for now.
Since then CP67 was called VM, and
for years IBM's internal computing
was done on about 3600 mainframes around the world and
all running VM/CMS and connected
with VNET which was a lot like the
Internet except the communications
were via bisync lines and the routing
was done by the mainframes themselves.
No, that setup didn't depend on
Systems Network Architecture (SNA).
Yes, there were a lot of fora!
The advantages of running on VM were
too good to pass up, so eventually
essentially all production IBM
mainframes were running their
operating systems as guests
on VM on the bare metal.
In virtual machine, IBM was way out
in front.