FOCAL-69 was the landmark version of the FOCAL programming language, more widely publicized than the original version of the language created in 1968. FOCAL-69, created by Richard Merrill is important because:
It was the basis for all later derivatives of the language (some of which branched off from one another)
It was the language the classic BASIC game Hamurabi was first written in
It became a popular language on Russian microcomputers.
Merrill clearly derived FOCAL-69 from JOSS:
FOCAL-69 borrows the JOSS innovation of requiring every line of the program to have a line number. (Prior to that, FORTRAN had optional line numbers.)
FOCAL-69 line numbers, like JOSS line numbers and unlike Dartmouth BASIC line numbers, were real numbers rather than integers.
The DO, SET and TYPE commands are simplified versions of the corresponding JOSS commands.
FOCAL-69 was a concise simplification of JOSS, with the simplicity required for the PDP-8, a minicomputer as opposed to the mainframe that JOSS was developed for.
The syntax is less wordy (e.g., "DO PART 20" becomes "DO 20").
The syntax is simpler (e.g., the JOSS statement "SET S=P, P=Q, Q=S" requires three statements in FOCAL-69: "SET S=P; SET P=Q; SET Q=S").
Shorter words are substituted for longer commands, and command words are designed to each have a unique first letter. So JOSS "DEMAND" becomes FOCAL-69 "ASK" (abbreviation A, as D would collide with DO) and JOSS "STOP" becomes "QUIT" (as "SET" was in use).
IF statements may not be appended to other statements.
FOCAL-69 had only a single built-in looping keyword ("FOR" as opposed to "WHILE").
Some early (non-standard) MUMPS implementations took ideas from FOCAL before the ANSI Standardization of MUMPS.
