Library
Register binary values:
ddd sss | Register Name |
rp | Register Pair | ccc | Condition | ||
000 | B | 00 | BC | 000 | NZ | ||
001 | C | 01 | DE | 001 | Z | ||
010 | D | 10 | HL | 010 | NC | ||
011 | E | 11 | SP, PSW | 011 | C | ||
100 | H | 100 | PO(dd) | ||||
101 | L | 101 | PE(ven) | ||||
110 | M | 110 | P(lus) | ||||
111 | A | 111 | M(inus) |
Register "M" refers to the memory location addressed by the HL register pair.
The register pair SP is used with LXI and DAD. The register pair PSW is used with PUSH and POP.
This section describes all the instuctions in the 8080A instruction set. See above for the values to substitute for sss, ddd, rp, and ccc in the descriptions below. "nnn" refers to a non-register numeric value given by the instruction operand.
Data Transfer Group |
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Mnemonic | Opcode | Cycles | Flags Affected | Description | |
MOV r1,r2 | 01dddsss | 5 | none | Copies the contents of register r2 to r1. | |
MOV M,r2 | 01110sss | 7 | none | Copies the contents of register r2 to the byte addressed by the (HL) register pair. | |
MOV r1,M | 01ddd110 | 7 | none | Copies the contents of the byte addressed by the (HL) register pair to r1. | |
MVI r1,data | 00ddd110 | 7 | none | The content of the 2nd byte of the instruction (immediate data) is copied into the named register. | |
MVI M,data | 00110110 | 10 | none | The content of the 2nd byte of the instruction (immediate data) is copied into the byte addressed by the (HL) register pair. | |
LXI rp,data | 00rp0001 | 10 | none | The content of byte 2 and 3 of the instruction (immediate data) is copied into the named register pair. | |
LDA addr | 00111010 | 13 | none | The content of the memory byte addressed by bytes 2 and 3 of the instruction are copied to register A. | |
STA addr | 00110010 | 13 | none | The content of register A is copied to the memory byte addressed by bytes 2 and 3 of the instruction. | |
LHLD addr | 00101010 | 16 | none | The content of the word (16 bits) at the address in bytes 2 and 3 of the instruction are copied to the HL register pair. | |
SHLD addr | 00100010 | 16 | none | The content of register pair HL are copied to the word (16 bits) at the address given in bytes 2 and 3 of the instruction. | |
LDAX rp | 00rp1010 | 7 | none | The content of the byte at the address found in the register pair (BC or DE only) is copied to register A. | |
STAX rp | 01rp0010 | 7 | none | The content of register A is copied to memory at the address found in the register pair (BC or DE only). | |
XCHG | 11101011 | 4 | none | The contents of the HL and DE register pairs are swapped. | |
Arithmetic Group |
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Mnemonic | Opcode | Cycles | Flags Affected | Description | |
ADD r | 10000sss | 4 | Z,S,P,C,AC | The register is added to register A. | |
ADD M | 10000110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is added to register A. | |
ADI data | 11000110 | 7 | Z,S,P,C,AC | Instruction byte 2 (immediate data) is added to register A. | |
ADC r | 10001sss | 4 | Z,S,P,C,AC | The register and the Carry flag are added to register A. | |
ADC M | 10001110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair and the Carry flag are added to register A. | |
ACI data | 11001110 | 7 | Z,S,P,C,AC | Instruction byte 2 (immediate data) and the Carry flag are added to Register A. | |
SUB r | 10010sss | 4 | Z,S,P,C,AC | The register is subtracted from register A. | |
SUB M | 10010110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is subtracted from register A. | |
SUI data | 10010110 | 7 | Z,S,P,C,AC | Instruction byte 2 (immediate data) is subtracted from register A. | |
SBB r | 10011sss | 4 | Z,S,P,C,AC | The register and the Carry flag are subtracted from register A. | |
SBB M | 10011110 | 0 | Z,S,P,C,AC | The byte addressed by the (HL) register pair and the Carry flag are subtracted from register A. | |
SBI data | 11011110 | 7 | Z,S,P,C,AC | Instruction byte 2 (immediate data) and the Carry flag are subtracted from register A. | |
INR r | 00ddd100 | 4 | Z,S,P,AC | The register is incremented. Note that Carry is not affected. | |
INR M | 00110100 | 10 | Z,S,P,AC | The byte addressed by the (HL) register pair is incremented. Note that Carry is not affected. | |
DCR r | 00ddd101 | 4 | Z,S,P,AC | The register is decremented. Note that Carry is not affected. | |
DCR M | 00110101 | 10 | Z,S,P,AC | The byte addressed by the (HL) register pair is decremented. Note that Carry is not affected. | |
INX rp | 00rp0011 | 5 | none | The register pair is incremented as a 16-bit number. | |
DCX rp | 00rp1011 | 5 | none | The register pair is decremented as a 16-bit number. | |
DAD rp | 00rp1001 | 10 | C | The register pair is added to the HL register pair. | |
DAA | 00100111 | 4 | Z,S,P,C,AC | Register A is adjusted to form two BCD digits as follows: (1) If the value of the least significant 4 bits of register A is greater than 9 or if the AC flag is set, 6 is added to the accumulator. (2) If the value of the most significant 4 bits of register A is now greater than 9 or if the C flag is set, 6 is added to the most significant 4 bits of register A. |
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Logical Group |
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Mnemonic | Opcode | Cycles | Flags Affected | Description | |
ANA r | 10100sss | 4 | Z,S,P,C,AC | The register is anded with register A. | |
ANA M | 10100110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is anded with register A. | |
ANI data | 11100110 | 7 | Z,S,P,C,AC | The 2nd byte of the instruction (immediate data) is anded with register A. | |
XRA r | 10101sss | 4 | Z,S,P,C,AC | The register is exclusive-or'd with register A. | |
XRA M | 10101110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is exclusive-or'd with register A. | |
XRI data | 11101110 | 7 | Z,S,P,C,AC | The 2nd byte of the instruction (immediate data) is exclusive-or'd with register A. | |
ORA r | 10110sss | 4 | Z,S,P,C,AC | The register is or'd with register A. | |
ORA M | 10110110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is or'd with register A. | |
ORI data | 11110110 | 7 | Z,S,P,C,AC | The 2nd byte of the instruction (immediate data) is or'd with register A. | |
CMP r | 10111sss | 4 | Z,S,P,C,AC | The register is subtracted from register A and the result discarded; register A remains unchanged. The flags are set based on the result of this subtraction. | |
CMP M | 10111110 | 7 | Z,S,P,C,AC | The byte addressed by the (HL) register pair is subtracted from register A and the result discarded; register A remains unchanged. The flags are set based on the result of this subtraction. | |
CPI data | 11111110 | 7 | Z,S,P,C,AC | The 2nd byte of the instruction (immediate data) is subtracted from register A and the result discarded; register A remains unchanged. The flags are set based on the result of this subtraction. | |
RLC | 00000111 | 4 | C | The contents of register A are shifted left one bit. Both the low-order bit and flag C are set to the value shifted out of the high-order bit. (This is an 8-bit rotate into Carry.) | |
RRC | 00001111 | 4 | C | The contents of register A are shifted right one bit. Both the high-order bit and flag C are set to the value shifted out of the low-order bit. (This is an 8-bit rotate into Carry.) | |
RAL | 00010111 | 4 | C | The contents of register A are shifted left one bit. The low-order bit is set to the value of flag C. Flag C is set to the value shifted out of the high-order bit. (This is a 9-bit rotate through Carry.) | |
RAR | 00011111 | 4 | C | The contents of register A are shifted right one bit. The high-order bit is set to the value of flag C. Flag C is set to the value shifted out of the low-order bit. (This is a 9-bit rotate through Carry.) | |
CMA | 00101111 | 4 | none | The contents of register A are complemented: the 1 bits become 0 and the 0 bits become 1. | |
CMC | 00111111 | 4 | C | The Carry flag is complemented. | |
STC | 00110111 | 4 | C | The Carry flag is forced to 1. | |
Branch Group |
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Mnemonic | Opcode | Cycles * | Flags Affected | Description | |
JMP addr | 11000011 | 10 | none | Control is passed to the instruction at the given address. | |
J(condition) | 11ccc010 | 10 | none | If the specified condition is true, control is passed to the instruction at the given address. | |
CALL | 11001101 | 17 | none | The next instruction address is pushed on the stack. Then control passes to the instruction at the given address. | |
C(condition) | 11ccc100 | 11/17 | none | If the specified condition is true, the next instruction address is pushed on the stack. Then control passes to the instruction at the given address. | |
RET | 11001001 | 5 | none | Control is passed to the address that is popped from the stack. | |
R(condition) | 11ccc000 | 5/11 | none | If the specified condition is true, control is passed to the address that is popped from the stack. | |
RST n | 11nnn111 | 11 | none | The next instruction address is pushed onto the stack. Then control is passed to the instruction at address 'n' * 8. (The program counter is set to the value 0000 0000 00nn n000.) | |
PCHL | 11101001 | 5 | none | The contents of register pair HL are copied to the program counter, effectively passing control to the instruction at the address in HL. | |
Stack, I/O and Machine Control Group |
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Mnemonic | Opcode | Cycles | Flags Affected | Description | |
PUSH rp | 11rp0101 | 11 | none | The named register pair is pushed onto the stack. | |
POP rp | 11rp0001 | 10 | (note) | The named register pair is popped off of the stack. | |
XTHL | 11100011 | 18 | none | The contents of the HL pair are swapped with the 16-bit value at the top of the stack. | |
SPHL | 11111001 | 5 | none | The contents of the HL pair are copied into the SP pair. | |
IN port | 11011011 | 10 | none | The port named in the 2nd byte of the instruction (immediate data) is read and the data placed in register A. | |
OUT port | 11010011 | 10 | none | The data in register A is written to the port addressed in the 2nd byte of the instruction (immediate data). | |
EI | 11111011 | 4 | none | The interrupt system is enabled, following the execution of the next instruction. | |
DI | 11110011 | 4 | none | The interrupt system is disabled immediately. | |
HLT | 01110110 | 7 | none | The processor is halted. This condition persists until the next interrupt. | |
NOP | 00000000 | 4 | none | No operation is performed. |
See also:
file: /Techref/intel/8080.htm, 25KB, , updated: 2018/11/6 11:26, local time: 2024/8/21 11:12,
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