DR805X Datasheet, PDF (15/79 Pages) Digital Core Design – 8-bit RISC Microcontroller Instructions set details ver 3.10

DR805x Instructions set details
3.2. ADD
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Instruction: ADD A, <src-byte>
Function:
Adds A to the source operand and returns the result to A.
Description:
ADD adds the byte variable indicated to the accumulator, leaving the
result in the accumulator. The carry and auxiliary carry flags are set,
respectively, if there is a carry out of bit 7 or bit 3, and cleared
otherwise. When adding unsigned integers, the carry flag indicates an
overflow occurred. OV is set if there is a carry out of bit 6 but not out of
bit 7, or a carry out of bit 7 but not out of bit 6; otherwise OV is cleared.
When adding signed integers, OV indicates a negative number
produced as the sum of two positive operands, or a positive sum from
two negative operands. Four source operand addressing modes are
allowed: register, direct, register- indirect, or immediate.
3.2.1. ADD A, RN
Operation: (PC) ← (PC) + 1
(A) ← (A) + (Rn)
Bytes:
1
Cycles:
2
Encoding:
00101 r r r
3.2.2. ADD A, DIRECT
Operation: (PC) ← (PC) + 2
(A) ← (A) + (direct)
Bytes:
2
Cycles:
3
Encoding:
00100101
direct address
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