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2 Instructions
2-174
CP1E CPU Unit Instructions Reference Manual(W483)
Subtraction at (1)
Subtraction at (2)
Final Subtraction Result
Sample program
If the result of the subtraction is a negative number (Mi<Su or Mi+1, Mi <Su+1, Su), the result is output
as a 10’s complement. The Carry Flag (CY) will turn ON. To convert the 10’s complement to the true
number, a program which subtracts the result from 0 is necessary, as an input condition of the Carry
Flag (CY). The Carry Flag turning ON thus indicates that the result of the subtraction is negative.
0
1
–
9
7
5
0
8
7
3
2
9
6
6
4
0
1
Mi+1: CIO 201
CY
S1: CIO 200
Su+1: CIO 121 S2: CIO 120
9251 13191
R+1: D101 R+1: D100
09583960+(100000000-17072641)
The Carry Flag (CY) is ON, so the result is subtracted from 0000 0000.
0
–
0 0 0 0 0 0 0
Su+1: D101 Su: D100
9 2 5 1 1 3 1 9
00000000+(100000000-92511319)
CY
0 7 4 8 8 6 8 11
R+1: D101 R+1: D100
–
CY
1
R+1: D101 R+1: D100
Mi+1: CIO 201 Mi: CIO 200
Su+1: D101 Su: D100
0 9 5 8 3 9 6 0
1 7 0 7 2 6 4 1
0 7 4 8 8 6 8 1
The Carry Flag (CY) will be turned ON, so the actual number is
– 7,488,681. Because the content of D101 and D100 is negative, CY is
used to turn ON CIO 21.00 to indicate this.
−B
D100
D110
D120
0.00
When CIO 0.00 is ON in the following example, D110 is subtracted from
D100 as 4-digit BCD values, and the result will be output to D120.
−BL
D100
D110
D120
0.00
When CIO 0.00 is ON in the following example, D111 and D110 will be
subtracted from D101 and D100 as 8-digit BCD values, and the result will
be output to D121 and D120.