Z80

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Zilog Z80A

Microprocessor from Zilog, which is used in the Amstrad CPC Computers. The Z80/Z80A was a very popular microprocessor, used in a great variety of home computers and appliances as far-fetched as satellites. It was even used in the Commodore C128 as a secondary processor in order to achieve CP/M compatibility.

Description

The Z80 microprocessor is an 8 bit CPU with a 16 bit address bus capable of direct access to 64k of memory space. It has a language of 252 root instructions and with the reserved 4 bytes as prefixes, access to an additional 308 instructions. The Z80 was modelled after the 8080 and contains the seventy-eight 8080 opcodes as a subset to its language.

Programming features include an accumulator and six 8-bit registers that can be paired as three 16-bit registers. In addition to the general registers, a stack pointer, program counter, and two index (memory pointer) registers are provided. While not in the same league as the Intel 80x86 or the Motorola 68000 series, the Z80 is extremely useful for low cost control applications. One of the more useful features of the Z80 is the built-in refresh circuitry for ease of design with DRAMs.

The Z80 comes in a 40 pin DIP package. It has been manufactured in A, B, and C models, differing only in maximum clock speed. It also has been manufactured as a stand-alone microcontroller with various configurations of on-chip RAM and EPROM.

Part numbers used in the Amstrad CPC during its lifetime

The Z80 CPU has been manufactured by others, and various Z80s have been used in the construction of the CPC during its lifetime.

  • SGS Z8400AB1
  • ST Z8400AB1
  • ZILOG Z8400APS
  • ZILOG Z0840004PSC

modern incarnatinons

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Apart from surplus/new Z80-clones that are quite easy to find, many emulations depend on software implementations of the Z80:

  • The T80 is a VHDL implementation of the Z80 and Z80A, finished in 2002 on OpenCores
  • arnold uses InkZ80, written in C++ (apart from the author-designed C simulation)
  • On OpenCores, there is also a Verilog implementation of the Z80.

Zilog itself offers the eZ80 processor, a new, 50MHz design. Kits now have reached a less-than-prohibitive price range and may be available without a business.

See also

Tutorials

Weblinks

Opcodes

Check the end of the document for explanations of abbreviations used below.

Alfabethical list

Mnemonic Clock Size SZHPNC Opcode Description Notes
ADC A, r 4 1 *** V0 * 88 + rb Add with Carry A = A + s + CY
ADC A, N 7 2 CE XX
ADC A, (HL) 7 1 8E
ADC A, (IX + N) 19 3 DD 8E XX
ADC A, (IY + N) 19 3 FD 8E XX
ADC HL, BC 15 2 **? V0 * ED 4A Add with Carry HL = HL + ss + CY
ADC HL, DE 15 2 ED 5A
ADC HL, HL 15 2 ED 6A
ADC HL, SP 15 2 ED 7A
ADD A, r 4 1 *** V0 * 80 + rb Add (8-bit) A = A + s
ADD A, N 7 2 C6 XX
ADD A, (HL) 7 1 86
ADD A, (IX + N) 19 3 DD 86 XX
ADD A, (IY + N) 19 3 FD 86 XX
ADD HL, BC 11 1 --?- 0 * 09 Add (16-bit) HL = HL + ss
ADD HL, DE 11 1 19
ADD HL, HL 11 1 29
ADD HL, SP 11 1 39
ADD IX, BC 15 2 --?- 0 * DD 09 Add (IX register) IX = IX + pp
ADD IX, DE 15 2 DD 19
ADD IX, IX 15 2 DD 29
ADD IX, SP 15 2 DD 39
ADD IY, BC 15 2 --?- 0 * FD 09 Add (IY register) IY = IY + rr
ADD IY, 15 2 FD 19
ADD IY, IY 15 2 FD 29
ADD IY, SP 15 2 FD 39
AND r 4 1 ***P00 A0+rb Logical AND A=A&s
AND N 7 2 E6 XX
AND (HL) 7 1 A6
AND (IX+N) 19 3 DD A6 XX
AND (IY+N) 19 3 FD A6 XX
BIT b,r 8 2 ?*1?0- CB 40+8*b+rb Test Bit m&{2^b}
BIT b,(HL) 12 2 CB 46+8*b
BIT b,(IX+N) 20 4 DD CB XX 46+8*b
BIT b,(IY+N) 20 4 FD CB XX 46+8*b
CALL NN 17 3 ------ CD XX XX Unconditional Call -(SP)=PC,PC=nn
CALL C,NN 17/1 3 ------ DC XX XX Conditional Call If Carry = 1
CALL NC,NN 17/1 3 D4 XX XX If carry = 0
CALL M,NN 17/1 3 FC XX XX If Sign = 1 (negative)
CALL P,NN 17/1 3 F4 XX XX If Sign = 0 (positive)
CALL Z,NN 17/1 3 CC XX XX If Zero = 1 (ans.=0)
CALL NZ,NN 17/1 3 C4 XX XX If Zero = 0 (non-zero)
CALL PE,NN 17/1 3 EC XX XX If Parity = 1 (even)
CALL PO,NN 17/1 3 E4 XX XX If Parity = 0 (odd)
CCF 4 1 --?-0* 3F Complement Carry Flag CY=~CY
CP r 4 1 ***V1* B8+rb Compare Compare A-s
CP N 7 2 FE XX
CP (HL) 7 1 BE
CP (IX+N) 19 3 DD BE XX
CP (IY+N) 19 3 FD BE XX
CPD 16 2 ****1- ED A9 Compare and Decrement A-(HL),HL=HL-1,BC=BC-1
CPDR 21/1 2 ****1- ED B9 Compare, Dec., Repeat CPD till A=(HL)or BC=0
CPI 16 2 ****1- ED A1 Compare and Increment A-(HL),HL=HL+1,BC=BC-1
CPIR 21/1 2 ****1- ED B1 Compare, Inc., Repeat CPI till A=(HL)or BC=0
CPL 4 1 --1-1- 2F Complement A=~A
DAA 4 1 ***P-* 27 Decimal Adjust Acc. A=BCD format (dec.)
DEC A 4 1 ***V1- 3D Decrement (8-bit) s=s-1
DEC B 4 1 05
DEC C 4 1 0D
DEC D 4 1 15
DEC E 4 1 1D
DEC H 4 1 25
DEC L 4 2 2D
DEC (HL) 11 1 35
DEC (IX+N) 23 3 DD 35 XX
DEC (IY+N) 23 3 FD 35 XX
DEC BC 6 1 ------ 0B Decrement (16-bit) ss=ss-1
DEC DE 6 1 1B
DEC HL 6 1 2B
DEC SP 6 1 3B
DEC IX 10 2 ------ DD 2B Decrement xx=xx-1
DEC IY 10 2 FD 2B
DI 4 1 ------ F3 Disable Interrupts
DJNZ $+2 13/8 1 ------ 10 Dec., Jump Non-Zero B=B-1 till B=0
EI 4 1 ------ FB Enable Interrupts
EX (SP),HL 19 1 ------ E3 Exchange (SP)<->HL
EX (SP),IX 23 2 DD E3 (SP)<->xx
EX (SP),IY 23 2 FD E3
EX AF,AF' 4 1 08 AF<->AF'
EX DE,HL 4 1 EB DE<->HL
EXX 4 1 ------ D9 Exchange qq<->qq' (except AF)
HALT 4 1 ------ 76 Halt
IM 0 8 2 ------ ED 46 Interrupt Mode (n=0,1,2)
IM 1 8 2 ED 56
IM 2 8 2 ED 5E
IN A,(N) 11 2 ------ DB XX Input A=(n)
IN (C) 12 2 ***P0- ED 70 Input* (Unsupported)
IN A,(C) 12 2 ***P0- ED 78 Input r=(C)
IN B,(C) 12 2 ED 40
IN C,(C) 12 2 ED 48
IN D,(C) 12 2 ED 50
IN E,(C) 12 2 ED 58
IN H,(C) 12 2 ED 60
IN L,(C) 12 2 ED 68
INC A 4 1 ***V0- 3C Increment (8-bit) r=r+1
INC B 4 1 04
INC C 4 1 0C
INC D 4 1 14
INC E 4 1 1C
INC H 4 1 24
INC L 4 1 2C
INC BC 6 1 ------ 03 Increment (16-bit) ss=ss+1
INC DE 6 1 13
INC HL 6 1 23
INC SP 6 1 33
INC IX 10 2 ------ DD 23 Increment xx=xx+1
INC IY 10 2 FD 23
INC (HL) 11 1 ***V0- 34 Increment (indirect) (HL)=(HL)+1
INC (IX+N) 23 3 ***V0- DD 34 XX Increment (xx+d)=(xx+d)+1
INC (IY+N) 23 3 FD 34 XX
IND 16 2 ?*??1- ED AA Input and Decrement (HL)=(C),HL=HL-1,B=B-1
INDR 21/1 2 ?1??1- ED BA Input, Dec., Repeat IND till B=0
INI 16 2 ?*??1- ED A2 Input and Increment (HL)=(C),HL=HL+1,B=B-1
INIR 21/1 2 ?1??1- ED B2 Input, Inc., Repeat INI till B=0
JP NN 10 3 ------ C3 XX XX Unconditional Jump PC=nn
JP (HL) 4 1 E9 PC=(HL)
JP (IX) 8 2 DD E9 PC=(xx)
JP (IY) 8 2 FD E9
JP C,$NN 10/1 3 ------ DA XX XX Conditional Jump If Carry = 1
JP NC,$NN 10/1 3 D2 XX XX If Carry = 0
JP M,$NN 10/1 3 FA XX XX If Sign = 1 (negative)
JP P,$NN 10/1 3 F2 XX XX If Sign = 0 (positive)
JP Z,$NN 10/1 3 CA XX XX If Zero = 1 (ans.= 0)
JP NZ,$NN 10/1 3 C2 XX XX If Zero = 0 (non-zero)
JP PE,$NN 10/1 3 EA XX XX If Parity = 1 (even)
JP PO,$NN 10/1 3 E2 XX XX If Parity = 0 (odd)
JR $N+2 12 2 ------ 18 XX Relative Jump PC=PC+e
JR C,$N+2 12/7 2 ------ 38 XX Cond. Relative Jump If cc JR(cc=C,NC,NZ,Z)
JR NC,$N+2 12/7 2 30 XX
JR Z,$N+2 12/7 2 28 XX
JR NZ,$N+2 12/7 2 20 XX
LD I,A 9 2 ------ ED 47 Load* dst=src
LD R,A 9 2 ED 4F
LD A,I 9 2 **0*0- ED 57 Load* dst=src
LD A,R 9 2 ED 5F
LD A,r 4 1 ------ 78+rb Load (8-bit) dst=src
LD A,N 7 2 3E XX
LD A,(BC) 7 1 0A
LD A,(DE) 7 1 1A
LD A,(HL) 7 1 7E
LD A,(IX+N) 19 3 DD 7E XX
LD A,(IY+N) 19 3 FD 7E XX
LD A,(NN) 13 3 3A XX XX
LD B,r 4 1 40+rb
LD B,N 7 2 06 XX
LD B,(HL) 7 1 46
LD B,(IX+N) 19 3 DD 46 XX
LD B,(IY+N) 19 3 FD 46 XX
LD C,r 4 1 48+rb
LD C,N 7 2 0E XX
LD C,(HL) 7 1 4E
LD C,(IX+N) 19 3 DD 4E XX
LD C,(IY+N) 19 3 FD 4E XX
LD D,r 4 1 50+rb
LD D,N 7 2 16 XX
LD D,(HL) 7 1 56
LD D,(IX+N) 19 3 DD 56 XX
LD D,(IY+N) 19 3 FD 56 XX
LD E,r 4 1 58+rb
LD E,N 7 2 1E XX
LD E,(HL) 7 1 5E
LD E,(IX+N) 19 3 DD 5E XX
LD E,(IY+N) 19 3 FD 5E XX
LD H,r 4 1 60+rb
LD H,N 7 2 26 XX
LD H,(HL) 7 1 66
LD H,(IX+N) 19 3 DD 66 XX
LD H,(IY+N) 19 3 FD 66 XX
LD L,r 4 1 68+rb
LD L,N 7 2 2E XX
LD L,(HL) 7 1 6E
LD L,(IX+N) 19 3 DD 6E XX
LD L,(IY+N) 19 3 FD 6E XX
LD BC,(NN) 20 4 ------ ED 4B XX XX Load (16-bit) dst=src
LD BC,NN 10 3 01 XX XX
LD DE,(NN) 20 4 ED 5B XX XX
LD DE,NN 10 3 11 XX XX
LD HL,(NN) 20 3 2A XX XX
LD HL,NN 10 3 21 XX XX
LD SP,(NN) 20 4 ED 7B XX XX
LD SP,HL 6 1 F9
LD SP,IX 10 2 DD F9
LD SP,IY 10 2 FD F9
LD SP,NN 10 3 31 XX XX
LD IX,(NN) 20 4 DD 2A XX XX
LD IX,NN 14 4 DD 21 XX XX
LD IY,(NN) 20 4 FD 2A XX XX
LD IY,NN 14 4 FD 21 XX XX
LD (HL),r 7 1 ------ 70+rb Load (Indirect) dst=src
LD (HL),N 10 2 36 XX
LD (BC),A 7 1 02
LD (DE),A 7 1 12
LD (NN),A 13 3 32 XX XX
LD (NN),BC 20 4 ED 43 XX XX
LD (NN),DE 20 4 ED 53 XX XX
LD (NN),HL 16 3 22 XX XX
LD (NN),IX 20 4 DD 22 XX XX
LD (NN),IY 20 4 FD 22 XX XX
LD (NN),SP 20 4 ED 73 XX XX
LD (IX+N),r 19 3 DD 70+rb XX
LD (IX+N),N 19 4 DD 36 XX XX
LD (IY+N),r 19 3 FD 70+rb XX
LD (IY+N),N 19 4 FD 36 XX XX
LDD 16 2 --0*0- ED A8 Load and Decrement (DE)=(HL),HL=HL-1,#
LDDR 21/1 2 --000- ED B8 Load, Dec., Repeat LDD till BC=0
LDI 16 2 --0*0- ED A0 Load and Increment (DE)=(HL),HL=HL+1,#
LDIR 21/1 2 --000- ED B0 Load, Inc., Repeat LDI till BC=0
NEG 8 2 ***V1* ED 44 Negate A=-A
NOP 4 1 ------ 00 No Operation
OR r 4 1 ***P00 B0+rb Logical inclusive OR A=Avs
OR N 7 2 F6 XX
OR (HL) 7 1 B6
OR (IX+N) 19 3 DD B6 XX
OR (IY+N) 19 3 FD B6 XX
OUT (N),A 11 2 ------ D3 XX Output (n)=A
OUT (C),0 12 2 ED 71 Output* (Unsupported)
OUT (C),A 12 2 ED 79 Output (C)=r
OUT (C),B 12 2 ED 41
OUT (C),C 12 2 ED 49
OUT (C),D 12 2 ED 51
OUT (C),E 12 2 ED 59
OUT (C),H 12 2 ED 61
OUT (C),L 12 2 ED 69
OUTD 16 2 ?*??1- ED AB Output and Decrement (C)=(HL),HL=HL-1,B=B-1
OTDR 21/1 2 ?1??1- ED BB Output, Dec., Repeat OUTD till B=0
OUTI 16 2 ?*??1- ED A3 Output and Increment (C)=(HL),HL=HL+1,B=B-1
OTIR 21/1 2 ?1??1- ED B3 Output, Inc., Repeat OUTI till B=0
POP AF 10 1 ------ F1 Pop qq=(SP)+
POP BC 10 1 C1
POP DE 10 1 D1
POP HL 10 1 E1
POP IX 14 2 ------ DD E1 Pop xx=(SP)+
POP IY 14 2 FD E1
PUSH AF 11 1 ------ F5 Push (SP)=qq
PUSH BC 11 1 C5
PUSH DE 11 1 D5
PUSH HL 11 1 E5
PUSH IX 15 2 ------ DD E5 Push -(SP)=xx
PUSH IY 15 2
RES b,r 8 2 ------ CB 80+8*b+rb Reset bit m=m&{~2^b}
RES b,(HL) 15 2 CB 86+8*b
RES b,(IX+N) 23 4 DD CB XX 86+8*b
RES b,(IY+N) 23 4 FD CB XX 86+8*b
RET 10 1 ------ C9 Return PC=(SP)+
RET C 11/5 1 D8 Conditional Return If Carry = 1
RET NC 11/5 1 D0 If Carry = 0
RET M 11/5 1 F8 If Sign = 1 (negative)
RET P 11/5 1 F0 If Sign = 0 (positive)
RET Z 11/5 1 C8 If Zero = 1 (ans.=0)
RET NZ 11/5 1 C0 If Zero = 0 (non-zero)
RET PE 11/5 1 E8 If Parity = 1 (even)
RET PO 11/5 1 E0 If Parity = 0 (odd)
RET 10 1 ------ C9 Return PC=(SP)+
RET C 11/5 1 ------ D8 Conditional Return If Carry = 1
RET NC 11/5 1 D0 If Carry = 0
RET M 11/5 1 F8 If Sign = 1 (negative)
RET P 11/5 1 F0 If Sign = 0 (positive)
RET Z 11/5 1 C8 If Zero = 1 (ans.=0)
RET NZ 11/5 1 C0 If Zero = 0 (non-zero)
RET PE 11/5 1 E8 If Parity = 1 (even)
RET PO 11/5 1 E0 If Parity = 0 (odd)
RETI 14 2 ------ ED 4D Return from Interrupt PC=(SP)+
RETN 14 2 ------ ED 45 Return from NMI PC=(SP)+
RLA 4 1 --0-0* 17 Rotate Left Acc. A={CY,A}<-
RL r 8 2 **0P0* CB 10+rb Rotate Left m={CY,m}<-
RL (HL) 15 2 CB 16
RL (IX+N) 23 4 DD CB XX 16
RL (IY+N) 23 4 FD CB XX 16
RLCA 4 1 --0-0* 07 Rotate Left Cir. Acc. A=A<-
RLC r 8 2 **0P0* CB 00+rb Rotate Left Circular m=m<-
RLC (HL) 15 2 CB 06
RLC (IX+N) 23 4 DD CB XX 06
RLC (IY+N) 23 4 FD CB XX 06
RLD 18 2 **0P0- ED 6F Rotate Left 4 bits {A,(HL)}={A,(HL)}<- ##
RRA 4 1 --0-0* 1F Rotate Right Acc. A=->{CY,A}
RR r 8 2 **0P0* CB 18+rb Rotate Right m=->{CY,m}
RR (HL) 15 2 CB 1E
RR (IX+N) 23 4 DD CB XX 1E
RR (IY+N) 23 4 FD CB XX 1E
RRCA 4 1 --0-0* 0F Rotate Right Cir.Acc. A=->A
RRC r 8 2 **0P0* CB 08+rb Rotate Right Circular m=->m
RRC (HL) 15 2 CB 0E
RRC (IX+N) 23 4 DD CB XX 0E
RRC (IY+N) 23 4 FD CB XX 0E
RRD 18 2 **0P0- ED 67 Rotate Right 4 bits {A,(HL)}=->{A,(HL)} ##
RST 0 11 1 ------ C7 Restart (p=0H,8H,10H,...,38H)
RST 08H 11 1 CF
RST 10H 11 1 D7
RST 18H 11 1 DF
RST 20H 11 1 E7
RST 28H 11 1 EF
RST 30H 11 1 F7
RST 38H 11 1 FF
SBC r 4 1 ***V1* 98+rb Subtract with Carry A=A-s-CY
SBC A,N 7 2 DE XX
SBC (HL) 7 1 9E
SBC A,(IX+N) 19 3 DD 9E XX
SBC A,(IY+N) 19 3 FD 9E XX
SBC HL,BC 15 2 **?V1* ED 42 Subtract with Carry HL=HL-ss-CY
SBC HL,DE 15 2 ED 52
SBC HL,HL 15 2 ED 62
SBC HL,SP 15 2 ED 72
SCF 4 1 --0-01 37 Set Carry Flag CY=1
SET b,r 8 2 ------ CB C0+8*b+rb Set bit m=mv{2^b}
SET b,(HL) 15 2 CB C6+8*b
SET b,(IX+N) 23 4 DD CB XX C6+8*b
SET b,(IY+N) 23 4 FD CB XX C6+8*b
SLA r 8 2 **0P0* CB 20+rb Shift Left Arithmetic m=m*2
SLA (HL) 15 2 CB 26
SLA (IX+N) 23 4 DD CB XX 26
SLA (IY+N) 23 4 FD CB XX 26
SRA r 8 2 **0P0* CB 28+rb Shift Right Arith. m=m/2
SRA (HL) 15 2 CB 2E
SRA (IX+N) 23 4 DD CB XX 2E
SRA (IY+N) 23 4 FD CB XX 2E
SLL r 8 2 **0P0* CB 30+rb Shift Left Logical* m={0,m,CY}<-

(SLL Instructions are unsupported)

SLL (HL) 15 2 CB 36
SLL (IX+N) 23 4 DD CB XX 36
SLL (IY+N) 23 4 FD CB XX 36
SRL r 8 2 **0P0* CB 38+rb Shift Right Logical m=->{0,m,CY}
SRL (HL) 15 2 CB 3E
SRL (IX+N) 23 4 DD CB XX 3E
SRL (IY+N) 23 4 FD CB XX 3E
SUB r 4 1 ***V1* 90+rb Subtract A=A-s
SUB N 7 2 D6 XX
SUB (HL) 7 1 96
SUB (IX+N) 19 3 DD 96 XX
SUB (IY+N) 19 3 FD 96 XX
XOR r 4 1 ***P00 A8+rb Logical Exclusive OR A=Axs
XOR N 7 2 EE XX
XOR (HL) 7 1 AE
XOR (IX+N) 19 3 DD AE XX
XOR (IY+N) 19 3 FD AE XX

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