10 Mar
2023
10 Mar
'23
2:27 p.m.
The first mainframe I worked on was single user,
single tasking and all jobs were
submitted as "batch" as in a batch of cards. :-)
Second Mainframe I worked on supported lots of users but to the user it was
still small amount of interactive and the rest batch. multi-user was done thru
VM370 which made it look like we all were the only users on out machine.
Third Mainframe I worked on was primarily interactive with many user during
the day and then ran lots of batch jobs at night.
The last mainframe I worked on was a 9020/9X2, some time in '95 or '96 maybe - the
biggest S390 IBM made, and for a while, I could use it as my personal computer (in fact, a
memo was sent across the organisation I worked in that one of the issues with the
regulatory bodies had been caused by 'some persons regarding the production mainframes
as their personal toy') although that happened already before the 9020 generation
Not that the 9020/9X2 was all play though. One of my duties was to narrate tours of the
data center, and I usually built up the narrative to showing the nice and big dials of the
water cooling. There were three - inlet temp, outlet temp, and flow, IIRC. But I
hadn't been there on the weekend the 9X2 was delivered, and I kind of assumed that the
dials would be behind the same door. Took me 3 tries to find them...
But another thing I remember from that tour is that I opened the door on one of the CPU
frames, but not as usual on the side where the water cooling was visible - the TCM array
of 4x4, with that many red and blue hoses. On the other side you had the power supplies,
also in a 4x4 array - and probably more impressive if you read the labels. '3.3V
500A', that kind of thing - not sure I remember correctly, it might've been 300A.
But whichever, 16 of those, and then times 10 for all 10 CPUs.
That made the distinction between mini and mainframe quite clear to me. Sure there's a
very broad middle ground, but nothing I ever saw in the mini space was remotely on the
same playing field as this stuff.
-- my n=1, cheers all!
Sytse