CP/M Internals

The reason most people are still drawn to CP/M is because it is so easy to fully understand the system, up from the tiniest detail. Yet, CP/M is the direct predecessor of MS-DOS (which was modeled very closely after CP/M) and has full functionality for normal use. If you know CP/M, you understand the low-level basics of any PC, and it gives you a level of understanding of the hardware that you'd never gain with, for instance, Linux. In short, understanding CP/M is relatively easy, and it gives you an insight in today's computers that is hard to obtain in any other way. CP/M essentially provides programs with a set of function calls that allow them to communicate with the computer's I/O devices in a standardized manner. These system calls (the BDOS functions) ensure that user programs never have to bother with how the computer hardware stores a file or puts text on a screen - instead, the system calls can be relied upon to do the job. That concept is the basis for any operat...