Building a programming language for a small computer: Reinventing the wheel

The language SP-12 for a PDP-12 computer is described. SP-12 is an example of how a special-purpose language can be constructed from a set of machine-language subroutines that are called by a simple interpreter. Symbolic source programs make it easy to learn the language. Preliminary translation of the source program into binary code, using an assembler, greatly increases the speed of the interpreter.