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OX, V15 10:57 22-FEB-68 PAGE 30

FROM MUP AND PUP, MUP AND PUP LOAD
WHEN UPDATE IS CALLED, U1 HAS ONLY
THE PIECE MOVING SET U2, CONTAINS
UPDATE USES THIS NUMBER TO DETERMINE
REGISTER I HAS BITS SET TO ENABLE
THE WORD IN THE CASE OF BRANCHING
S A, P, AND K MUST BE LOADED WITH
N BEFORE EITHER MUP OR PUP IS CALLED

;ADD 1 TO RETURN ADDRESS
;A IS NOW PASSIVE & P IS NOW ACTIVE
;IS PIECE MOVING A KING?
;YES
;SKIP IF U2 GREATER THAN 0
;SET FORWARD BIT
;SET BACKWARD
;ZERO BIT'S POSITION
;DO IT AGAIN & TEST FOR JUMP
;SET JUMP FLAG

;SHIFT AGAIN BY MAGIC NUMBER
;SET DESTINATION BIT
;SO THAT "IDNN" CAN BE USED 5 LINES DOWN
;DOES PIECE WANT TO BE A KING?
;NO
;IS PIECE ALREADY A KING?
;NO, SO TURN OFF JUMP FLAG
;IS PIECE A KING?
;YES, SO ST DESTINATION BIT
;WAS MOVE A JUMP?
;NO, SO RETURN
;KLUDGE RESET
;HAVE MULTIPLE JUMPS ALREADY BEEN FOUND?
;NO
;YES, BUT FROM PREVIOUS MOVE?
:YES

;BUILD MASK WORD IN U3
;PIECE CAN'T MOVE FORWARD
;RF POSITION

is column is picking up bits?
B.P.