THE EVOLUTION OF THE DECsystem-10 495
access for temporary and common sub-expressions, top of stack when accessed explicitly, pointer-to-control stacks, and fast registers to hold small programs.
Since the ACs were in the address space, ordinary memory could be used in lieu of fast registers to reduce the minimal machine price. In reality, nearly all users bought fast registers. Eight registers may have been enough. A small number would have provided more rapid context switching and assisted the assembly language programmer who tried to optimize (and