ASM, the CP/M Assembler and DDT
P. E. Gosling · 1985
If you really want to get to the “heart” of a computer system then it is necessary to learn to talk to it in, as near as possible, a language that it understands. Using high-level programming languages such as MBASIC means that you are talking to the computer through an interpreter and hence all the instructions that you issue in a program take that much longer to be carried out. That is why we use a compiler; see chapter 8. But even if we use a compiled language we cannot control a number of aspects of the computer’s operation at what we could call the “bit level”. This is the lowest level of communication with the microprocessor and in the past, when computers were still in their infancy, this was the only way of programming. It was actually performed in the binary code of zeros and ones. This is not surprising since this is the only kind of code that the processor understands. High-level languages have taken a lot of the hard work out of programming, but a lot of detail has been lost on the way.