Atlas Autocode
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.