A-27
INSTRUCTION SET REFERENCE
Hex Code in: Binary Mode = [Encoding]
Source Mode = [Encoding]
Operation: ACALL
(PC) ← (PC) + 2
(SP) ← (SP) + 1
((SP)) ← (PC.7:0)
(SP) ← (SP) + 1
((SP)) ← (PC.15:8)
(PC.10:0) ← page address
ADD <dest>,<src>
Function: Add
Description: Adds the source operand to the destination operand, which can be a register or the accumu-
lator, leaving the result in the register or accumulator. If there is a carry out of bit 7 (CY), the
CY flag is set. If byte variables are added, and if there is a carry out of bit 3 (AC), the AC flag
is set. For addition of unsigned integers, the CY flag indicates that an overflow occurred.
If there is a carry out of bit 6 but not out of bit 7, or a carry out of bit 7 but not bit 6, the OV
flag is set. When adding signed integers, the OV flag indicates a negative number produced
as the sum of two positive operands, or a positive sum from two negative operands.
Bit 6 and bit 7 in this description refer to the most significant byte of the operand (8, 16, or 32
bit).
Four source operand addressing modes are allowed: register, direct, register-indirect, and
immediate.
Flags:
Example: Register 1 contains 0C3H (11000011B) and register 0 contains 0AAH (10101010B). After
executing the instruction
ADD R1,R0
register 1 contains 6DH (01101101B), the AC flag is clear, and the CY and OV flags are set.
Variations
ADD A,#data
Binary Mode Source Mode
Bytes: 22
States: 11
[Encoding] a10 a9 a8 1 0 0 0 1 a7 a6 a5 a4 a3 a2 a1 a0
CY AC OV N Z
✓✓✓✓✓
[Encoding] 0 0 1 0 0 1 0 0 immed. data
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