
FOCAL (acronym for Formulating On-line Calculations in Algebraic Language, 
or FOrmula CALculator) is an interactive interpreted programming 
language based on JOHNNIAC Open Shop System (JOSS) and mostly used on 
Digital Equipment Corporation (DEC) Programmed Data Processor (PDP) 
series machines.

FOCAL (acronym for Formulating On-line Calculations in Algebraic Language,
 or FOrmula CALculator) is an interactive interpreted programming language 
based on JOHNNIAC Open Shop System (JOSS) and mostly used on Digital 
Equipment Corporation (DEC) Programmed Data Processor (PDP) series 
machines. FOCAL is very similar to JOSS in the commands it supports 
and the general syntax of the language. It differs in that many of 
JOSS' advanced features like ranges and user-defined functions were 
removed to simplify the parser. Some of the reserved words (keywords) 
were renamed so that they all start with a unique first letter. 
This allows users to type in programs using one-character statements, 
further reducing memory needs. This was an important consideration 
on the PDP-8, which was often limited to a few kilobytes (KB). 
Like JOSS, and later BASICs, FOCAL on the PDP-8 was a complete 
environment that included a line editor, an interpreter, and 
input/output routines. The package as a whole was named FOCAL-8, 
which also ran on the PDP-5 and PDP-12. When ported to the PDP-11, 
the resulting FOCAL-11 relied on the underlying operating system, 
RT-11, to provide file support and editing. The language definition 
was updated twice, to FOCAL-69 and a very slightly modified FOCAL-71. 
A port to the Intel 8080 was also available. FOCAL is notable as the 
language in which the original versions of the early video games 
Hamurabi and Lunar Lander were written. Both were later ported to 
BASIC, where they became much better known. FOCAL was not popular 
outside the PDP platform and largely disappeared during the move to 
the VAX-11. It had a strong revival in the Soviet Union where PDP-11 
clones were used as educational and home computers. (en)


Developer: Richard_Merrill_(computer_scientist)
Influenced: BASIC-Plus


Richard Merrill was a Digital Equipment Corporation employee who 
invented the FOCAL programming language and programmed the first 
two interpreters for the language in 1968 and 1969, for the PDP-8. 
He also developed later versions of the interpreter for the PDP-7 
and PDP-9, later ported it to the PDP-11. Merrill also designed 
and programmed the EDIT-8 text editor (using paper-tape). Rick Merrill 
is an alumnus of Episcopal High School, a preparatory school in 
Alexandria, VA and of M.I.T BS'63 MS'65 and Clark University MBA'85 (en)



