Zilog Z80 Instruction Set
Instructions by Opcode
| Mnemonic | Description |
|---|---|
| b | Identifies a one-bit expression in the range (0 to 7). The most-significant bit to the left is bit 7 and the least-significant bit to the right is bit 0. |
| cc | Identifies the status of the Flag Register as any of (NZ, Z, NC, C, PO, PE, P, or M) for the conditional jumps, calls, and return instructions. |
| Cy | Identifies the value of the Carry flag. |
| d | Identifies a one-byte signed integer expression in the range ( -128 to +127). |
| e | Identifies a one-byte signed integer expression in the range (-126 to +129) for relative jump offset from current location. |
| m | Identifies any one of r, (HL), (IX+d) or (IY+d). |
| n | Identifies a one-byte unsigned integer expression in the range (0 to 255). |
| nn | Identifies a two-byte unsigned integer expression in the range (0 to 65535). |
| pp | Identifies any one of the 16-bit registers BC, DE, IX, SP. |
| Identifies any one of the 16-bit registers BC, DE, HL, AF. | |
| r | Identifies any one of the 8-bit registers A, B, C, D, E, H, L. |
| rr | Identifies any one of the 16-bit registers BC, DE, IY, SP. |
| ss | Identifies any one of the 16-bit registers BC, DE, HL, SP. |
| (HL) | Identifies the contents of the memory location, whose address is specified by the contents of the register pair HL. |
| (IX+d) | Identifies the contents of the memory location, whose address is specified by the contents of the IX Index Register plus the signed displacement d. |
| (IY+d) | Identifies the contents of the memory location, whose address is specified by the contents of the IY Index Register plus the signed displacement d. |
| x0 | Identifies a single bit of the mnemonic. |
| x0-2 | Identifies a range of bits of the mnemonic. |
| A′ | Identifies a shadow register, which are not directly accessible. |
| ← | Identifies an assignment to a target such as a register or memory location. |
| •
∧ & |
AND Operation |
| +
∨ || |
OR Operation |
| ⊕
⊻ |
Exclusive OR (XOR) Operation |
| ¬
~ |
Negation |
| << | Bitwise left-shift operation |
| >> | Bitwise right-shift operation |
| Port(y:x) | Identifies the operation of reading or writing to an I/O port, with y denoting the upper byte and x denoting the lower byte of the I/O address. The upper byte of the I/O address is never able to be directly provided, it either is the value of the A register or 00h in the case of IN0/OUT0 on the Z180 processor. |
| Registers | Value |
|---|---|
| B | 000 |
| C | 001 |
| D | 010 |
| E/(IX+d)[a] | 011 |
| H | 100 |
| L | 101 |
| (HL)[b] | 110 |
| A/(IY+d)[c] | 111 |
| Registers | Value |
|---|---|
| BC | 00 |
| DE | 01 |
| HL/IX[a]/IY[b] | 10 |
| SP | 11 |
Single-byte Instructions
| Opcode | Operands | Mnemonic | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | b2 | b3 | ||
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | — | — | NOP | No operation |
| 0 | 0 | rr | 0 | 0 | 0 | 1 | n-lo | n-hi | LD rr, nn | rr ← nn | |
| 0 | 0 | rr | 0 | 0 | 1 | 0 | — | — | LD (rr), A | rr ← A | |
| 0 | 0 | ss | 0 | 0 | 1 | 1 | — | — | INC ss | ss ← ss + 1 | |
| 0 | 0 | r | 1 | 0 | 0 | — | — | INC r | r ← r + 1 | ||
| 0 | 0 | r | 1 | 0 | 1 | — | — | DEC r | r ← r - 1 | ||
| 0 | 0 | r | 1 | 1 | 0 | n | — | LD r, n | r ← n | ||
| 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | — | — | RLCA | A1-7 ← A0-6, A0 ← Cy ← A7 |
| 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | — | — | EX AF,AF’ | AF ↔ AF’ |
| 0 | 0 | rr | 1 | 0 | 0 | 1 | — | — | ADD HL, rr | HL ← HL + rr | |
| 0 | 0 | rr | 1 | 0 | 1 | 0 | — | — | LD A, (rr) | A ← (rr) [BC or DE only] | |
| 0 | 0 | rr | 1 | 0 | 1 | 1 | — | — | DEC rr | rr ← rr - 1 | |
| 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | — | — | RRCA | A0-6 ← A1-7, A7 ← Cy ← A0 |
| 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | d | — | DJNZ d | B = B - 1; if B ≠ 0 then PC ← PC + d |
| 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | — | — | RLA | A1-7 ← A0-6, Cy ← A7, A0 ← Cy |
| 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | d | — | JR d | PC ← PC + d |
| 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | — | — | RRA | A0-6 ← A1-7, Cy ← A0, A7 ← Cy |
| 0 | 0 | 1 | cc | 0 | 0 | 0 | d | — | JR cc, d | If cc0-1 true, PC ← PC + d (Only 2 bits of cc used: NZ, Z, NC, C) | |
| 0 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | n-lo | n-hi | LD (nn), HL | (nn) ← HL |
| 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | — | — | DAA | @ |
| 0 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | n-lo | n-hi | LD HL, (nn) | HL ← (nn) |
| 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | — | — | CPL | A ← ¬A |
| 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | n-lo | n-hi | LD (nn), A | (nn) ← A |
| 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | — | — | SCF | Cy ← 1 |
| 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | n-lo | n-hi | LD A, (nn) | A ← (nn) |
| 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | — | — | CCF | Cy ← ¬Cy |
| 0 | 1 | r | r’ | — | — | LD r, r’ | r ← r’ | ||||
| 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | — | — | HALT | Halt CPU |
| 1 | 0 | 0 | 0 | 0 | r | — | — | ADD r | A ← A + r | ||
| 1 | 0 | 0 | 0 | 1 | r | — | — | ADC r | A ← A + r + Cy | ||
| 1 | 0 | 0 | 1 | 0 | r | — | — | SUB r | A ← A – r | ||
| 1 | 0 | 0 | 1 | 1 | r | — | — | SBC r | A ← A – r – Cy | ||
| 1 | 0 | 1 | 0 | 0 | r | — | — | AND r | A ← A • r | ||
| 1 | 0 | 1 | 0 | 1 | r | — | — | XOR r | A ← A ⊕ r | ||
| 1 | 0 | 1 | 1 | 0 | r | — | — | OR r | A ← A + r | ||
| 1 | 0 | 1 | 1 | 1 | r | — | — | CP r | A ← A – r | ||
| 1 | 1 | cc | 0 | 0 | 0 | — | — | RET cc | If cc true, PC ← (SP), SP ← SP + 2 | ||
| 1 | 1 | rr | 0 | 0 | 0 | 1 | — | — | POP rr | rr ← (SP), SP ← SP + 2 | |
| 1 | 1 | cc | 0 | 1 | 0 | n-lo | n-hi | JP cc, nn | If cc true, PC ← nn | ||
| 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | n-lo | n-hi | JP nn | PC ← nn |
| 1 | 1 | cc | 1 | 0 | 0 | n-lo | n-hi | CALL cc, nn | If cc true, SP ← SP - 2, (SP) ← PC, PC ← nn | ||
| 1 | 1 | rr | 0 | 1 | 0 | 1 | — | — | PUSH rr | SP ← SP - 2, (SP) ← rr | |
| 1 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | n | — | ADD n | A ← A + n |
| 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | n | — | ADC n | A ← A + n + Cy |
| 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | n | — | SUB n | A ← A – n |
| 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | n | — | SBC n | A ← A – n – Cy |
| 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | n | — | AND n | A ← A • n |
| 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | n | — | XOR n | A ← A ⊕ n |
| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | n | — | OR n | A ← A + n |
| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | n | — | CP n | A ← A – n |
| 1 | 1 | n | 1 | 1 | 1 | — | — | RST n | SP ← SP - 2, (SP) ← PC, PC ← n | ||
| 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | — | — | RET | PC ← (SP), SP ← SP + 2 |
| 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | CB Prefix | |||
| 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | n-lo | n-hi | CALL nn | SP ← SP - 2, (SP) ← PC, PC ← nn |
| 1 | 1 | 0 | 1 | 0 | 0 | 1 | 1 | n | — | OUT n | PORT(A:n) ← A |
| 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | — | — | EXX | BC ↔ BC′, DE ↔ DE′, HL ↔ HL′ |
| 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | n | — | IN n | A ← PORT(A:n) |
| 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | IX Prefix | |||
| 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | — | — | EX (SP), HL | (SP) ↔ HL |
| 1 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | — | — | JP (HL) | PC ← HL |
| 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | — | — | EX DE, HL | DE ↔ HL |
| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | ED Prefix | |||
| 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | — | — | DI | IFF1 ← IFF2 ← 0, disable interrupts |
| 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | — | — | LD SP, HL | SP ← HL |
| 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | — | — | EI | IFF1 ← IFF2 ← 1, enable interrupts |
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | IY Prefix | |||
Bit Function Instructions (CB Prefix)
| Opcode | Mnemonic | Description | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | ||
| 0 | 0 | 0 | 0 | 0 | r | RLC r | r1-7 ← r0-6, r0 ← Cy ← r7 | ||
| 0 | 0 | 0 | 0 | 1 | r | RRC r | r0-6 ← r1-7, r7 ← Cy ← r0 | ||
| 0 | 0 | 0 | 1 | 0 | r | RL r | r1-7 ← r0-6, Cy ← r7, r0 ← Cy | ||
| 0 | 0 | 0 | 1 | 1 | r | RR r | r0-6 ← r1-7, Cy ← r0, r7 ← Cy | ||
| 0 | 0 | 1 | 0 | 0 | r | SLA r | Cy ← r7, r1-7 ← r0-6, r0 ← 0 | ||
| 0 | 0 | 1 | 0 | 1 | r | SRA r | Cy ← r0, r0-6 ← r1-7 | ||
| 0 | 0 | 1 | 1 | 1 | r | SRL r | Cy ← r0, r0-6 ← r1-7, r7 ← 0 | ||
| 0 | 1 | b | r | BIT b,r | r ∧ (1 << b) | ||||
| 1 | 0 | b | r | RES b,r | r ← r ∧ ¬(1 << b) | ||||
| 1 | 1 | b | r | SET b,r | r ← r ∨ (1 << b) | ||||
Miscellaneous Instructions (ED Prefix)
| Opcode | Operands | Mnemonic | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | b2 | b3 | ||
| 0 | 0 | r | 0 | 0 | 0 | — | — | IN0 r, (n) | r ← Port(00h:n)[a] | ||
| 0 | 0 | r | 0 | 0 | 1 | — | — | OUT0 r, (n) | Port(00h:n) ← r[a] | ||
| 0 | 0 | r | 1 | 0 | 0 | TST r | A • B[b] | ||||
| 0 | 1 | r | 0 | 0 | 0 | — | — | IN r,(C)[c] | r ← Port(BC) [Except (HL)] (Port number is 16 bits) | ||
| 0 | 1 | r | 0 | 0 | 1 | — | — | OUT (C), r | Port(BC) ← r [Except (HL)] (Port number is 16 bits) | ||
| 0 | 1 | rr | 0 | 0 | 1 | 0 | — | — | SBC HL, rr | HL ← HL – rr – Cy | |
| 0 | 1 | rr | 0 | 0 | 1 | 1 | n-lo | n-hi | LD (nn), rr | (nn) ← rr | |
| 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | — | — | NEG | A ← 0 - A |
| 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | — | — | RETN | PC ← (SP), SP ← SP + 2, IFF1 ← IFF2[d] |
| 0 | 1 | 0 | n | 1 | 1 | 0 | — | — | IM n | Interrupt mode 0, 1, 2 (encoded 0, 2, 3) | |
| 0 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | — | — | LD I, A | interrupt control vector ← A |
| 0 | 1 | rr | 1 | 0 | 1 | 0 | — | — | ADC HL, rr | HL ← HL + rr + CY | |
| 0 | 1 | rr | 1 | 0 | 1 | 1 | n-lo | n-hi | LD rr, (nn) | rr ← (nn) | |
| 0 | 1 | rr | 1 | 1 | 0 | 0 | — | — | MLT rr | rr ← rr0-7 × rr8-15 | |
| 0 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | — | — | RETI | PC ← (SP), SP ← SP + 2, IFF1 ← IFF2[d] |
| 0 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | — | — | LD R, A | refresh ← A |
| 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | — | — | LD A, I | A ← interrupt control vector [e] |
| 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | — | — | LD A, R | A ← refresh [e] |
| 0 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | — | — | RRD | A0-3 ← (HL)0-3, (HL)7-4 ← A0-3, (HL)0-3 ← (HL)7-4 |
| 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | — | — | RLD | A0-3 ← (HL)7-4, (HL)0-3 ← A0-3, (HL)7-4 ← (HL)0-3 |
| 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | — | — | TST n | A • n |
| 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | — | — | TSTIO n | Port(C) • n |
| 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | — | — | SLP | Sleep |
| 1 | 0 | 0 | R | D | 0 | 1 | 1 | OTIM OTDM OTIMR OTMDR | Port(C) ← (HL), HL ← HL ± 1, C ← C ± 1, B ← B - 1 | ||
| 1 | 0 | 1 | R | D | 0 | 0 | 0 | — | — | LDI LDIR LDD LDDR | (DE) ← (HL), HL ← HL ± 1, DE ← DE ± 1, BC ← BC - 1 [f][g] |
| 1 | 0 | 1 | R | D | 0 | 0 | 1 | — | — | CPI CPIR CPD CPDR | A - (HL), HL ← HL ± 1, BC ← BC - 1 [f][g][h] |
| 1 | 0 | 1 | R | D | 0 | 1 | 0 | — | — | INI INIR IND INDR | (HL) ← Port(B:C), HL ← HL ± 1, B ← B – 1 [f] |
| 1 | 0 | 1 | R | D | 0 | 1 | 1 | — | — | OUTI OTIR OUTD OTDR | B ← B – 1, Port(B:C) ← (HL), HL ← HL ± 1 [f][1] |
- ↑ 1.0 1.1 Excludes (HL) register.
- ↑ Flags are modified when the operation executes, but the A register is not updated.
- ↑ Byte input sets the flags unlike IN A, n.
- ↑ 4.0 4.1 RETN and RETI are identical and restore IFF1. Z80 compatible interrupt devices watch for RETI by sniffing the data bus while M1- is asserted for 0xED followed by 0x4D.
- ↑ 5.0 5.1 LD A, I and LD A, R are the only two LD instructions that set flags. Additionally, IFF2 is loaded into the P/V flag. C unaffected.
- ↑ 6.0 6.1 6.2 6.3 When D = 1, pointers HL and DE decrement. When R = 1, operation repeats until BC or B = 0. All block IO instructions output BC, not just C, as the port address.
- ↑ 7.0 7.1 LDI, LDD, CPI, and CPD set P/V if BC – 1 ≠ 0. This is useful for loop control when not using repeat.
- ↑ CPIR/CPDR terminate early if A = (HL).
Instructions by Group
8-bit Load Group
LD r, r
Operation
r, ← r′
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|
| 0 | 1 | ← r → | ← r’ → | ||||
Operands
r, r′
Description
The contents of any register r' are loaded to any other register r. r, r' identifies any of the registers A, B, C, D, E, H, or L.
Condition Bits Affected
- None.
Example
If the H Register contains the number 8Ah, and the E register contains 10h, the instruction LD H, E results in both registers containing 10h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 1 | 4 | 1.0 |
LD r, n
Operation
r ← n
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|
| 0 | 0 | ← r → | 1 | 1 | 0 | ||
| ← n → | |||||||
Operands
r, n
Description
The 8-bit integer n is loaded to any register r, in which r identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
- None.
Example
Upon the execution of an LD E, A5h instruction, Register E contains A5h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 2 | 7 (4, 3) | 1.75 |
LD r, (HL)
Operation
r ← (HL)
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|
| 0 | 1 | ← r → | 1 | 1 | 0 | ||
Operands
r, (HL)
Description
The 8-bit contents of memory location (HL) are loaded to register r, in which r identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
- None.
Example
If register pair HL contains the number 75A1h, and memory address 75A1h contains byte 58h, the execution of LD C, (HL) results in 58h in Register C.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 2 | 7 (4, 3) | 1.75 |
LD r, (IX+d)
Operation
r ← (IX+d)
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | DD |
| 0 | 1 | ← r → | 1 | 1 | 0 | |||
| ← d → | ||||||||
Operands
r, (IX+d)
Description
The (IX+d) operand (i.e., the contents of Index Register IX summed with two’s-complement displacement integer d) is loaded to register r, in which r identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
- None.
Example
If Index Register IX contains the number 25AFh, the instruction LD B, (IX+19h) allows the calculation of the sum 25AFh + 19h, which points to memory location 25C8h. If this address contains byte 39h, the instruction results in Register B also containing 39h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 5 | 19 (4, 4, 3, 5, 3) | 2.50 |
LD r, (IY+d)
Operation
r ← (IY+d)
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | FD |
| 0 | 1 | ← r → | 1 | 1 | 0 | |||
| ← d → | ||||||||
Operands
r, (lY+d)
Description
The operand (lY+d) loads the contents of Index Register IY summed with two’s-complement displacement integer, d, to register r, in which r identifies registers A, B, C, D, E, H, or L. Condition Bits Affected
- None.
Example
If Index Register IY contains the number 25AFh, the instruction LD B, (IY+19h) allows the calculation of the sum 25AFh + 19h, which points to memory location 25C8h. If this address contains byte 39h, the instruction results in Register B also containing 39h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 5 | 19 (4, 4, 3, 5, 3) | 2.75 |
LD (HL), r
Operation
(HL) ← r
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|
| 0 | 1 | 1 | 1 | 0 | ← r → | ||
Operands
(HL), r
Description
The contents of register r are loaded to the memory location specified by the contents of the HL register pair. The r symbol identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
- None.
Example
If the contents of register pair HL specify memory location 2146h and Register B contains byte 29h, then upon the execution of an LD (HL), B instruction, memory address 2146h also contains 29h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 2 | 7 (4, 3) | 1.75 |
LD (IX+d), r
Operation
(IX+d) ← r
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | DD |
| 0 | 1 | 1 | 1 | 0 | ← r → | |||
| ← d → | ||||||||
Operands
(IX+d), r
Description
The contents of register r are loaded to the memory address specified by the contents of Index Register IX summed with d, a two’s-complement displacement integer. The r symbol identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
None.
Example
If the C register contains byte 1Ch, and Index Register IX contains 3100h, then the instruction LID (IX + 6h), C performs the sum 3100h + 6h and loads 1Ch to memory location 3106h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 5 | 19 (4, 4, 3, 5, 3) | 4.75 |
LD (IY+d), r
Operation
(IY+d) ← r
Op Code
LD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | FD |
| 0 | 1 | 1 | 1 | 0 | ← r → | |||
| ← d → | ||||||||
Operands
(IY+d), r
Description
The contents of resister r are loaded to the memory address specified by the sum of the contents of Index Register IY and d, a two’s-complement displacement integer. The r symbol identifies registers A, B, C, D, E, H, or L.
Condition Bits Affected
None.
Example
If the C register contains byte 1Ch, and Index Register IX contains 3100h, then the instruction LID (IX + 6h), C performs the sum 3100h + 6h and loads 1Ch to memory location 3106h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 5 | 19 (4, 4, 3, 5, 3) | 4.75 |
16-bit Load Group
Exchange, Block Transfer, Search Group
General Purpose Arithmetic and CPU Control Group
NOP
Operation
—
Op Code
NOP
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 00 |
Operands
None.
Description
The CPU performs no operation during the machine cycle.
Condition Bits Affected
- None.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 1 | 4 | 1.0 |
8-bit Arithmetic Group
ADD A, r
Operation
A ← A + r
Op Code
ADD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|
| 1 | 0 | 0 | 0 | 0 | ← r → | ||
Operands
A, r
Description
The contents of register r are added to the contents of the Accumulator, and the result is stored in the Accumulator.
Condition Bits Affected
- S is set if result is negative; otherwise, it is reset.
- Z is set if result is 0; otherwise, it is reset.
- H is set if carry from bit 3; otherwise, it is reset.
- P/V is set if overflow; otherwise, it is reset.
- N is reset.
- C is set if carry from bit 7; otherwise, it is reset.
Example
If the Accumulator contains 44h and Register C contains 11h, then upon the execution of an ADD A, C instruction, the Accumulator contains 55h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 1 | 4 | 1.0 |
ADD A, n
Operation
A ← A + n
Op Code
ADD
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 1 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | C6 |
| ← n → | ||||||||
Operands
A, n
Description
The n integer is added to the contents of the Accumulator, and the results are stored in the Accumulator.
Condition Bits Affected
- S is set if result is negative; otherwise, it is reset.
- Z is set if result is 0; otherwise, it is reset.
- H is set if carry from bit 3; otherwise, it is reset.
- P/V is set if overflow; otherwise, it is reset.
- N is reset.
- C is set if carry from bit 7; otherwise, it is reset.
Example
If the Accumulator contains 23h, then upon the execution of an ADD A, 33h instruction, the Accumulator contains 56h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 2 | 7 (4, 3) | 1.75 |
ADD A, (HL)
Operation
A ← A + (HL)
Op Code
ADD
Operands
A, (HL)
Description
The byte at the memory address specified by the contents of the HL register pair is added to the contents of the Accumulator, and the result is stored in the Accumulator.
Condition Bits Affected
- S is set if result is negative; otherwise, it is reset.
- Z is set if result is 0; otherwise, it is reset.
- H is set if carry from bit 3; otherwise, it is reset.
- P/V is set if overflow; otherwise, it is reset.
- N is reset.
- C is set if carry from bit 7; otherwise, it is reset.
Example
If the Accumulator contains A0h, register pair HL contains 2323h, and memory location 2323h contains byte 08h, then upon the execution of an ADD A, (HL) instruction, the Accumulator contains A8h.
| M-Cyles | T-States | 4 MHz E.T. |
|---|---|---|
| 2 | 7 (4, 3) | 1.75 |
Rotate and Shift Group
Bit Set, Reset and Test Group
Jump Group
Call and Return Group
Input and Output Group
16-bit Arithmetic Group
- ↑ "Z80 Documentation Errors". CPC Wiki. Retrieved 28 November 2025. Unlike stated in Z80 documentation, OUTI OTIR OUTD OTDR decrement B before the IO access.