Bcd Subtract - Sub(31) - Omron CPM1 Programming Manual

BCD Calculation Instructions
Example
TR 0
00002
25504
25504
5-20-4 BCD SUBTRACT – SUB(31)
Limitations
Description
Flags
286
If 00002 is ON, the program represented by the following diagram clears CY
with CLC(41), adds the content of IR 030 to a constant (6103), places the
result in DM 0100, and then moves either all zeros or 0001 into DM 0101
depending on the status of CY (25504). This ensures that any carry from the
last digit is preserved in R+1 so that the entire result can be later handled as
eight-digit data.
Although two ADD(30) can be used together to perform eight-digit BCD addi-
tion, ADDL(54) is designed specifically for this purpose.
Ladder Symbols
SUB(31) @SUB(31)
Mi
Su
R
DM 6144 to DM 6655 cannot be used for R.
When the execution condition is OFF, SUB(31) is not executed. When the exe-
cution condition is ON, SUB(31) subtracts the contents of Su and CY from Mi,
and places the result in R. If the result is negative, CY is set and the 10's com-
plement of the actual result is placed in R. To convert the 10's complement to
the true result, subtract the content of R from zero (see example below).
Mi – Su – CY
ER: Mi and/or Su is not BCD.
Indirectly addressed DM word is non-existent. (Content of *DM word
is not BCD, or the DM area boundary has been exceeded.)
CY: ON when the result is negative, i.e., when Mi is less than Su plus CY.
EQ: ON when the result is 0.
Address Instruction
00000 LD
CLC(41)
00001 OUT
00002 CLC(41)
00003 AND(30)
ADD(30)
030
#6103
DM 0100
00004 AND
00005 MOV(21)
MOV(21)
#0001
DM 0101
00006 LD
00007 AND NOT
MOV(21)
00008 MOV(21)
#0000
DM 0101
IR, SR, AR, DM, HR, TC, LR, #
Su: Subtrahend word (BCD)
Mi
IR, SR, AR, DM, HR, TC, LR, #
Su
R
CY
Section 5-20
Operands
00002
TR 0
030
# 6103
DM 0100
25504
# 0001
DM 0101
TR 0
25504
# 0000
DM 0101
Operand Data Areas
Mi: Minuend word (BCD)
R: Result word
IR, SR, AR, DM, HR, LR
R