The author's comparison doesn't really work. The power of those IBM mainframes was in the entire architecture (SNA - System Network Architecture) not just the processing unit. Terminals such as the 3270 talked to cluster controllers that talked to batch controllers that talked to other controllers that fed the processor etc. (simplified).
Data making it's way through the device chain was nothing for a 3 MIPS processor with 64 MB of internal memory and 3MB IO to handle.
As far as IPL's were concerned, it was more common for the controllers to be IPL'd than it was for the processor. Because of heat and cooling issues, nobody ever wanted to shutdown the processing system or even let those boards deviate much from their operational temperature. Bad things always happened when they powered down and cooled off. Always.
Raspberry PI is better compared to a PDP-11, a VAX, or a Data General (Soul of a New Machine).
Why would cooling off cause problems? Stories like this make me feel as far removed from my computing ancestors as I feel from my farming grandparents.
As chips / boards / etc cool, they move and contract and (massive generalisation) this causes mechanical wear . I'm sure someone more versed in such stuff can give a detailed explanation of what can happen. (there are lots more side effects to power cycling gear as well)
Absolutely correct on all counts. Incidentally, for those with a Raspberry PI who want to run old hardware emulators (and indeed those of us without who still want to run them), you can't bear SIMH[1] which will happily emulate a PDP-11, VAX or Data General computer amongst others. You can even run old Unix on it!
Data making it's way through the device chain was nothing for a 3 MIPS processor with 64 MB of internal memory and 3MB IO to handle.
As far as IPL's were concerned, it was more common for the controllers to be IPL'd than it was for the processor. Because of heat and cooling issues, nobody ever wanted to shutdown the processing system or even let those boards deviate much from their operational temperature. Bad things always happened when they powered down and cooled off. Always.
Raspberry PI is better compared to a PDP-11, a VAX, or a Data General (Soul of a New Machine).