Comment by lproven

Your argument fails at its first line:

> An OS has to have drivers for diverse hardware already - an OS will be expected to support devices as varied as keyboards, mice, floppy drives, hard drives, VGA, PCI bus, etc.

No, it doesn't, because the OS we are talking about here is DOS.

APM was released in 1992: https://en.wikipedia.org/wiki/Advanced_Power_Management

This was before even Windows 3.1 shipped.

MS-DOS 5.0 was new and not that widely used but was catching on: https://en.wikipedia.org/wiki/Timeline_of_DOS_operating_syst...

DOS didn't support half the hardware you cite. It had no direct support for mice, CD-ROMs, PCI, VGA, or any of that. PCI 1.0 was released the same year.

In those days, most PC software used the BIOS to access standard hardware, and anything much past that was up to the vendor to ship a driver.

All APM really had to do was throttle the CPU and maybe, as a vendor extension, put the hard disk to sleep. That's about it.

Things like putting the display to sleep came along with the US Energy Star standard, released -- you guessed it -- in 1992.