VMS Help MACRO, VAX MACRO Assembler, Instructions, LDPCTX  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Purpose:        Load processor context - restore register and
                    memory management context
    Format:         opcode
    Operation:      if PSL<current-mode> NEQU 0 then {opcode reserved
                    to Digital fault}; {invalidate per-process
                    translation buffer entries}; {load process general
                    registers from process control block}; {load process
                    map, ASTLVL and PME from PCB}; {save PSL and PC on
                    stack for subsequent REI}
    C. Codes:       Not affected
    Exceptions:     Reserved operand, privileged instruction

    Opcodes:        06    LDPCTX   Load process context
    Description:    The process control block is specified by the
                    internal processor register PCBB (process control
                    block base). The general registers are loaded from
                    the PCB, along with the memory management registers
                    describing the address space. The process entries
                    in the translation buffer are cleared. Execution is
                    switched to the kernel stack. The PC and PSL are
                    moved from the PCB to the stack, suitable for use
                    by a REI instruction.