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32 lines
1.1 KiB
Plaintext
Executable File
32 lines
1.1 KiB
Plaintext
Executable File
MOON 0306 EST Friday, 7 November 1975
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PLAN FOR ONE PROCEED
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TO CAUSE A ONE-PROCEED, SET THE USER'S PC TO CONTAIN
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TRAP1+TRAP2+ADDR BRK INH (%PSTR1+%PSTR2+%PSINH).
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WHEN THE SYSTEM STARTS UP THE USER, THE JRST 12
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TURNS ON TRAP 3, TURNS OFF ADDR BRK INH, AND TURNS
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ON ADDR BRK CYCLE (SCD4 & SCD5). IF THE INSTRUCTION
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IS ABORTED ADDR BRK INH TURNS BACK ON, THE PC GETS SAVED
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WITH IT ON, THEN IT TURNS OFF. IF THE INSTRUCTION COMPLETES
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ADDR BRK INH AND ADDR BRK CYC GO OFF.
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NOW WHEN THE MICRO CODE SEES A TRAP, IT HAS TO CHECK
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IF IT IS TRAP 3 AND ADDR BRK CYC IS ON. IF SO, DON'T
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TAKE THE TRAP, JUST DO THE INSTRUCTION. SEE UCODE;BASIC .LOS
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FOR CODE TO NOT TAKE TRAPS.
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SCD ADDR BRK CYC IS BIT 4.4 OF DIAGNOSTIC READ 137.
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I DON'T THINK IT'S AVAILABLE ANY OTHER WAY, SO THAT MEANS
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HAVE TO GRAB ECL EBUS ETC ETC.
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THIS WINS BECAUSE HARDWARE MAINTAINS THE FLAG OF WHETHER
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THE INSTRUCTION HAS COMPLETED YET.
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IT LOSES BECAUSE THE "MAR" WILL BE DISABLED DURING A
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"ONE PROCEED." HOWEVER, THE FACT THAT IT ISN'T ON THE KA10
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CAN BE ANNOYING, ANYWAY, WHO CARES?
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THIS IS THE ONLY SIMPLE WAY TO DO ONE-PROCEED THAT I HAVE
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BEEN ABLE TO THINK OF.
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