Register - BCL Molecular 18

BCL Molecular 18
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Register Instructions

003001ALSB002001BLSBSkip if B1=0
003002AMSB002002BMSBSkip if B16=0
007600ANEG006600BNEGSkip if B17=1
007500AN0006500BN0Skip if not zero
007200APOS006200BPOSSkip if B17=0
007100A0006100B0Skip if zero
002400CLC Clear CARRY Flag
006004CLGT Clear GREATER THAN Flag
005004CLSA004004CLSBClear B17 (Sign bit)
004040COMPC Complement CARRY Flag
005002COMPSA004002COMPSBComplement B17 (Sign bit)
003010DECA002010DECBDecrement by one
005001ESWRA004001ESWRBEnter Switch Register (read Switches into)
003004INCA002004INCBIncrement by one
003240LRA002240LRBRotate Left by one (excluding B17)
003260LRAC002260LRBCRotate Left by one including CARRY (excluding B17)
001600+nLRAn000600+nLRBnRotate Left by n (excluding B17)
003300LSA002300LSBLeft Shift by one (excluding B17)
001700+nLSAn000700+nLSBnLeft Shift by n (excluding B17)
003040RRA002040RRBRotate Right by one (excluding B17)
003060RRAC002060RRBCRotate Right by one including CARRY (excluding B17)
001400+nRRAn000400+nRRBnRotate Right by n (excluding B17)
003100RSA002100RSBRight Shift by one (excluding B17)
001500+nRSAn000500+nRSBnRight Shift by n (excluding B17)
001520+nRSAAn000520+nRSABnRight Shift by n Arithmetic
005006SETSA004006SETSBSet B17 (Sign bit)
006440SKC Skip if CARRY Flag=1
006410SKGT Skip if GREATER THAN Flag=1
004020SKIP Skip unconditionally
006040SKNC Skip if CARRY Flag=0
006010SKNGT Skip if GREATER THAN Flag=0
005010SWAPA004010SWAPBSwap Bytes

The maximum value of n is 15 (decimal).

Micro-Programming Rules
Instructions on the same row in the above table may be combined in a single instruction, subject to the following:
  • Instructions will be executed in order from the left, except CLEAR SIGN which on some machines precedes CLEAR.
  • If skips are combined, the skip will occur only if all conditions are fulfilled, except if AMSB and ALSB (or BMSB and BLSB) are combined the skip will occur if either or both conditions are met.
  • The effect of combining SHIFT and ROTATE or INC and DEC is undefined.

For example:
005006 combines CLSA and COMPSA in that order to set the sign (B17) of the A-Register.
007502 combines AN0 and CLA to test for zero in, then clear, the A-Register.

(C) 2022 Kevin Murrell & The National Museum of Computing
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