BCPL

(language)(Basic CPL) A British systems language developed byRichards in 1969 and descended from CPL (CombinedProgramming Language). BCPL is low-level, typeless andblock-structured, and provides only one-dimensional arrays.Case is not significant, but conventionally reserved wordsbegin with a capital. Flow control constructs include:If-Then, Test-Then-Else, Unless-Do, While-Do, Until-Do,Repeat, Repeatwhile, Repeatuntil, For-to-By-Do, Loop, Breakand Switchon-Into-Case-Default-Endcase. BCPL has conditionalexpressions, pointers, and manifest constants. It has bothprocedures: 'Let foo(bar) Be command' and functions: 'Letfoo(bar) = expression'. 'Valof $(..Resultis..$)' causes acompound command to produce a value. Parameters arecall-by-value.

Program segments communicate via the global vector wheresystem and user variables are stored in fixed numericallocations in a single array.

The first BCPL compiler was written in AED. BCPL was usedto implement the TRIPOS operating system, which wassubsequently reincarnated as AmigaDOS.

["BCPL - The Language and its Compiler", Martin Richards &Colin Whitby-Stevens, Cambridge U Press 1979].

See OCODE, INTCODE.

Oxford BCPL differed slightly: Test-Ifso-Ifnot, and sectionbrackets in place of $( $).

The original INTCODE interpreter for BCPL is available forAmiga, Unix, MS-DOSftp://wuarchive.wustl.edu/systems/amiga/programming/languages/BCPL/.

A BCPL compiler bootstrap kit with an INTCODEinterpreter in C was written by Ken Yap.