Chapter Nine. Reminiscences on Hardware
ONE OF THE roles of an operating system is to insulate applications from hardware to some degree or other. This is hard enough with properly functioning hardware, but bad hardware makes the problem even more difficult. Here are some hardware-related stories, some dealing with bad hardware, and others just with the complexity of dealing with hardware in the first place, even the type that works just fine.
Hardware backward compatibility
BACKWARD COMPATIBILITY APPLIES not only to software. It also applies to hardware. And when hardware goes bad, the software usually takes the blame.
The HLT instruction tells the CPU to stop (“halt”) executing instructions until the next hardware interrupt. This is a big win ...