How did programming code exist?

Answer 1

Writing machine code by hand is extremely difficult, laborious and prone to human error. Machine code is the native language of the machine and is difficult for humans to interpret. To make it easier, programmers write simple translation programs that allow the computer to convert code written in a symbolic language into its own native machine code. Symbolic languages range from low-level to high-level. The more high-level, the easier it is for humans to read and maintain the code. High-level code is generally portable -- the same code can be translated for any machine that has a suitable translator.

At one time there were no programming languages at all, all machine code had to be written entirely by hand. However, the computer can easily be programmed to translate a low-level symbolic language using very little machine code. These primitive languages became known as assembly languages and the translation program became known as an assembler. Once we had one assembler for one type of machine, we could use it to create assemblers for other types of machine. We could also use the assembler to create better translators that could work with more complex symbolic languages. These complex translators went on to become the compilers and interpreters we see today.

Note that before we can program a new translator, we must first develop a language for it to translate. Typically the two will evolve together but we always start with the language, formalising its grammar or syntax and mapping the machine's instruction set to abstractions and language facilities that are more easily understood by humans. Once a language and its translator have evolved sufficiently it may be standardised, thus allowing other programmers to implement their own translators based upon the standard and thus ensuring the same source code will compile to machine code regardless of which translator is used.