(Basic CPL) A British systems language developed by Richards in 1969 and descended from CPL (Combined Programming Language). BCPL is low-level, typeless and block-structured, and provides only one-dimensional arrays. Case is not significant, but conventionally reserved words begin 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, Break and Switchon-Into-Case-Default-Endcase. BCPL has conditional expressions, pointers, and manifest constants. It has both procedures: 'Let foo(bar) Be command' and functions: 'Let foo(bar) = expression'. 'Valof $(..Resultis..$)' causes a compound command to produce a value. Parameters are call-by-value. Program segments communicate via the global vector where system and user variables are stored in fixed numerical locations in a single array. The first BCPL compiler was written in AED. BCPL was used to implement the TRIPOS operating system, which was subsequently reincarnated as AmigaDOS. See OCODE, INTCODE. Oxford BCPL differed slightly: Test-Ifso-Ifnot, and section brackets in place of $( $). A BCPL compiler bootstrap kit with an INTCODE interpreter in C was written by Ken Yap.