MOON 0306 EST  Friday, 7 November 1975

PLAN FOR ONE PROCEED

TO CAUSE A ONE-PROCEED, SET THE USER'S PC TO CONTAIN
TRAP1+TRAP2+ADDR BRK INH  (%PSTR1+%PSTR2+%PSINH).
WHEN THE SYSTEM STARTS UP THE USER, THE JRST 12
TURNS ON TRAP 3, TURNS OFF ADDR BRK INH, AND TURNS
ON ADDR BRK CYCLE (SCD4 & SCD5).  IF THE INSTRUCTION
IS ABORTED ADDR BRK INH TURNS BACK ON, THE PC GETS SAVED
WITH IT ON, THEN IT TURNS OFF.  IF THE INSTRUCTION COMPLETES
ADDR BRK INH AND ADDR BRK CYC GO OFF.

NOW WHEN THE MICRO CODE SEES A TRAP, IT HAS TO CHECK
IF IT IS TRAP 3 AND ADDR BRK CYC IS ON.  IF SO, DON'T
TAKE THE TRAP, JUST DO THE INSTRUCTION.  SEE UCODE;BASIC .LOS
FOR CODE TO NOT TAKE TRAPS.

SCD ADDR BRK CYC IS BIT 4.4 OF DIAGNOSTIC READ 137.
I DON'T THINK IT'S AVAILABLE ANY OTHER WAY, SO THAT MEANS
HAVE TO GRAB ECL EBUS ETC ETC.

THIS WINS BECAUSE HARDWARE MAINTAINS THE FLAG OF WHETHER
THE INSTRUCTION HAS COMPLETED YET.

IT LOSES BECAUSE THE "MAR" WILL BE DISABLED DURING A
"ONE PROCEED."  HOWEVER, THE FACT THAT IT ISN'T ON THE KA10
CAN BE ANNOYING, ANYWAY, WHO CARES?

THIS IS THE ONLY SIMPLE WAY TO DO ONE-PROCEED THAT I HAVE
BEEN ABLE TO THINK OF.
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