Zilog Z80380 - Manual (Page 206)

5-172
Z380 ™
U SER ' S M ANUAL
DC-8297-03
Z ILOG
SUB
SUBTRACT (BYTE)
SUB A,src src = R, RX, IM, IR, X
Operation: A
←
A - src
The source operand is subtracted from the accumulator and the difference is stored in the
accumulator. The contents of the source are unaffected. Two's complement subtraction is
performed.
Flags: S: Set if the result is negative; cleared otherwise
Z: Set if the result is zero; cleared otherwise
H: Set if there is a borrow from bit 4 of the result; cleared otherwise
V: Set if arithmetic overflow occurs, that is, if the operands are of different signs and the
result is of the same sign as the source; cleared otherwise
N: Set
C: Set if there is a borrow from the most significant bit of the result; cleared otherwise
Addressing Execute
Mode Syntax Instruction Format Time Note
R: SUB A,R 10010-r- 2
RX: SUB A,RX 11y11101 1001010w 2
IM: SUB A,n 11010110 ——n— 2
IR: SUB A,(HL) 10010110 2+r
X: SUB A,(XY+d) 11y11101 10010110 ——d— 4+r I
Field Encodings: r: per convention
y: 0 for IX, 1 for IY
w: 0 for high byte, 1 for low byte