Atlas Autocode

Atlas Autocode (AA) was a programming language developed around 1965 at Manchester University for the Atlas Computer. It was developed by Tony Brooker and Derrick Morris as an improvement on the ALGOL programming languages, removing some of Algol's poorer features such as passing parameters by name. It featured explicitly typed variables, subroutines and functions. The AA compiler generated range-checking for array accesses, and the language allowed an array to have dimensions that were determined at run-time (i.e. you could declare an array as integer array Thing (i:j), where i and j were calculated values). Atlas Autocode included a complex data type which would support complex numbers (for example, the square root of -1), a feature which was dropped when the language later morphed into the Edinburgh IMP programming language. (Imp was an extension of AA and was notable for being used to write the EMAS operating system.)
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<language> The Autocode for the Ferranti Atlas, which may have been the first commercial computer with hardware-paged virtual memory. Whereas other autocodes were basically assembly languages, Atlas Autocode was high-level and block-structured, resembling a cross between Fortran and ALGOL 60. It had call-by value, loops, declarations, complex numbers, pointers, heap and stack storage generators, dynamic arrays, and extensible syntax.
(2000-04-03)