FORTH By Wesley Morefield

History Worked at the Smithsonian Astrophysical Observatory. He used programs to allign satellite stations with astronomical positions. The formula for each satellite station was different, so he had to use different code for each one. In 1950 he created an interpreter so that he could have one main program and change out chunks of code for each satellite without recompiling the whole program.

Stack Stack based language. Reverse Polish Notation * STACKSTACKSTACK STACK

Control Structures

Dictionary Compiled list that remains in memory that contains all of the built-in and user created methods.  Example of how methods work and can be linked. ( Large letter F ) : STAR 42 EMIT ; ***** : STARS 0 DO STAR LOOP ;* : MARGIN CR 30 SPACES ;***** : BLIP MARGIN STAR ;* : BAR MARGIN 5 STARS ;* : F BAR BLIP BAR BLIP BLIP CR ;

Evaluation Readability Writability Reliability Cost

Readability

Writability

Reliability Unsafe Direct editing of memory Reliable when programmed correctly

Cost Language is free Not an easy language to learn Formal training would be expensive

References