NEC 78K/0 Series user manual SUB

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CHAPTER 5 EXPLANATION OF INSTRUCTIONS
User's Manual U12326EJ4V0UM
Subtract
SUB Byte Data Subtraction
[Instruction format] SUB dst, src
[Operation] dst, CY ← dst – src
[Operand]
Mnemonic Operand(dst,src) Mnemonic Operand(dst,src)
SUB A, #byte SUB A, !addr16
saddr, #byte A, [HL]
A, r Note A, [HL+byte]
r, A A, [HL+B]
A, saddr A, [HL+C]
Note Except r = A
[Flag]
ZACCY
×××
[Description]
• The source operand (src) specified by the 2nd operand is subtracted from the destination operand (dst)
specified by the 1st operand and the result is stored in the destination operand (dst) and the CY flag.
The destination operand can be cleared to 0 by equalizing the source operand (src) and the destination
operand (dst).
• If the subtraction shows that dst is 0, the Z flag is set (1). In all other cases, the Z flag is cleared (0).
• If the subtraction generates a borrow out of bit 7, the CY flag is set (1). In all other cases, the CY flag is
cleared (0).
• If the subtraction generates a borrow for bit 3 out of bit 4, the AC flag is set (1). In all other cases, the AC
flag is cleared (0).
[Description example]
SUB D, A; The A register is subtracted from the D register and the result is stored in the D register.