ZiLOG Z8 User Manual page 201

ZiLOG
SBC
SUBTRACT WITH CARRY
SBC
Subtract With Carry
SBC dst, src
Instruction Format:
Operation:
dst <— dst - src - C
The source operand, along with the setting of the C Flag, is subtracted from the destination operand and the result
is stored in the destination operand. The contents of the source operand are not affected. Subtraction is performed
by adding the two's complement of the source operand to the destination operand. In multiple precision arithmetic,
this instruction permits the carry (borrow) from the subtraction of low order operands to be subtracted from the
subtraction of high order operands.
Flags: C: Cleared if there is a carry from the most significant bit of the result; set otherwise, indicating a
"borrow."
Z: Set if the result is 0; cleared otherwise.
V: Set if arithmetic overflow occurred (if the operands were of opposite sign and the sign of the result is the
same as the sign of the source); reset otherwise.
S: Set if the result is negative; cleared otherwise.
H: Cleared if there is a carry from the most significant bit of the low order four bits of the result; set
otherwise indicating a "borrow."
D: Always set to 1.
Note:
Address modes R or IR can be used to specify a 4-bit Working Register. In this format, the source or destination
Working Register operand is specified by adding 1110B (EH) to the high nibble of the operand. For example, if
Working Register R12 (CH) is the destination operand, then ECH will be used as the destination operand in the Op
Code.
UM001601-0803
Z8 Microcontrollers
Instruction Descriptions and Formats
12-61