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Retrocomputing

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    That is an excellent answer. And, it makes total sense. I guess Commodore wasn't as stupid as I thought they were. Too bad they didn't design a better PSU before they potted it. :-) Commented Aug 7, 2017 at 17:22
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    The explanation I remember hearing at the time was it was done for safety reasons, maybe even specifically to get certification, and that the usual failure mode was that expansion and contraction would eventually crack the voltage regulator or break one of the connections. Commented Aug 7, 2017 at 17:43
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    Even without overloading those C64 PSUs died regularly. I used to fix them by piggy-backing a new 7805 on and replacing the removed case bottom with a generous heatsink - did at least two dozen of them. Commented Aug 7, 2017 at 19:27
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    FYI, "CBM" is Commodore Business Machines. Commented Aug 8, 2017 at 14:10
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    @RBarryYoung Thanks, but I know. If you are responding specifically to my internal quote note where I referred to "CP/M", I believe in that one instance Bil meant "CP/M cartridge" and not "CBM cartridge". The Z80 processor and other components within that cartridge would have added a noticeable load on the power supply, which in context is exactly what is being discussed at that point. FYI, Bil Herd is the lead engineer for the C= 128, and the one who decided to add the Z80 to its motherboard. So it makes sense that he would specifically reference the C64's CP/M cartridge. Commented Aug 8, 2017 at 16:41