Idle DR-DOS
I continue to be amazed by Michal Necasek's ability to deeply care about things that literally nobody has even thought about for decades. Kudos!Power management under DOS on early x86 laptops was downright primitive. There were no standards of any kind (I'd never even heard of the DR-DOS $IDLE$ device until now, but it doesn't seem like that gained any kind of traction at the time), not even BIOS-based abstractions. Just vendor-provided 'drivers' (in name only: it's not like DOS made any distinction between system and user code) that directly communicated with the hardware.Unsurprisingly, that all broke down as soon as you did anything even remotely interesting. Run QEMM386? No power management for you! Have a certain PCMCIA card inserted? Ditto! And shipping any kind of updates took forever at that time (literally FedExing floppies...), so getting a working system was pretty much impossible.