Mnemonic

Symbolic
Operation

Flags
S    Z    H   P/V  N    C

Opcode
76 543 210

Hex

Bytes

M
Cycles

Clock
Cycles

Comments

CCF

          ___
CY ¬ CY

•     •     X    •     0    ↕

00 111 111

3F

1

1

4

Complement
carry flag.

SCF

CY ¬ 1

•     •     0    •     0    1

00 110 111

37

1

1

4

NOP

No Operation

•     •     •     •     •     •

00 000 000

00

1

1

4

HALT

CPU halted

•     •     •     •     •     •

01 110 110

76

1

1

4

DI¹

IFF ¬ 0

•     •     •     •     •     •

11 110 011

F3

1

1

4

EI¹

IFF ¬ 1

•     •     •     •     •     •

11 111 011

FB

1

1

4

Notes:

The V symbol in the P/V flag column indicates that the P/V flag contains the overflow of the operation.
Similarly the P symbol indicates parity.
¹    No interrupts are issued directly after a DI or EI.
CY means the carry flag.

Flag Notation:

• = flag is not affected, 0 = flag is reset, 1 = flag is set, X = flag is “unknown”,
↕ = flag is set according to the result of the operation.