Toward user sharing of the microprogramming level under UNIX on the Perkin-Elmer 3220

Abstract

A master/slave model of writable control store is presented which is claimed to be a better representation of the operating system view of control store than models which more accurately portray the physical reality. Reported work includes the completed development of UNIX tools: an assembler generating relocatable, linkable microcode; a linking, relocating loader; a fast absolute loader; an interactive hard debugging aid allowing the setting of breakpoints; and alterations of the UNIX kernel allowing the driving of WCS as a “slave processor” consistent with the model. Code for the system driver and microcode portions of the debugger are included in the paper. The design goals of the multi-user sharing of control store, representing work now in progress, are listed. These include the use of the UNIX text segment management as the basis for association of control store routines with processes and the use of the debugging aid snapshot routines in the swapper.