Machine code is the sequence of binary-coded machine instructions specifically written to be used within machine language. Machine language is the low-level programming language that is directly read and interpreted by a computer's central processing unit (CPU) in order for it to perform its functions. The instructions within machine code are binary strings that may be either all the same size (e.g., one 32-bit word) or of different sizes (where the size of the instruction is determined from the first word or byte). For instance, when a CPU is set-up to use 32-bit words, it realizes that it only needs to scan that particular sequence of bits in order to perform all of its instructions.

Many of the computer programs "coded" by mathematical programmers from the mid-1940s to the late-1950s were written in the binary (base 2) numbering system--while some were written in octal...