ELE413

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ELE413

• 8085 Instruction Set
• Prepared by Kenan BOZDAS
• 28.10.2008

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Contents

• Registers
• Addressing Modes
• Instruction Set Classification
• Deeper look at instructions

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Registers

• Accumulator(A) Processor Status Word (PSW,Flag
  Register)
• B C (BC)
• D E (DE)
• H L (HL, M)
• Stack Pointer (SP)
• Program Counter (PC)

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Registers
Accumulator

• Destination for all Arithmetic Logical
  operations
• Dest Source for IN OUT instructions

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Registers
Flag Register (PSW)

• Flow control
• Status control
• Cannot access bits

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Registers
B, C, D, E

• Can be used as an 8-bit register
• Or in pairs
• B C (BC)
• D E (DE)

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Registers
H, L

• Can be used as an 8-bit register
• Or in pairs
• H L (HL)
• Or as a memory pointer (M)

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Registers
SP, PC

• Stack pointer is used in stack operations.
• Program counter contains the address of the
  instruction to be executed.

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Addressing Modes

• Immediate Addressing
• Register Addressing
• Direct Addressing
• Indirect Addressing

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Addressing Modes
Immediate Addressing

• Data is present in the instruction.
• MVI R,data (8-bit)
• LXI R-R,data (16-bit)

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Addressing Modes
Register Addressing

• Data is provided through the registers.
• MOV Rd,Rs

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Addressing Modes
Direct Addressing

• I/O instructions
• IN 01H
• OUT 21H
• Address is given in the instruction
• CALL 2000H
• STA 0FF00H

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Addressing Modes
Indirect Addressing

• Effective address is calculated by the processor
• DCR M HLHL-1
• LDAX B ABC

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Instruction Set Classification

• Data Transfer (Copy) Operations
• Arithmetic Operations
• Logical Operations
• Branching Operations
• Machine Control Operations

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Instruction Set Classification
Data Transfer(Copy) Operations

• Between Registers
• MOV D,L
• Specific data byte to a register or a memory
  location
• MVI C,0FAH
• MVI M,00H
• Between a memory location and a register
• MOV M,L
• Between an I/O device and the accumulator
• IN 21H

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Instruction Set Classification
Arithmetic Operations

• Addition
• ADD R AAR
• ADI 03H AA3H
• Subtraction
• SUB R AA-R
• SUI 15H AA-15H
• Increment/Decrement
• INR A
• DECX H

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Instruction Set Classification
Logical Operations

• AND, OR, XOR
• ANA R AAR
• XRA M AA M
• Rotate
• RAL
• RRC
• Compare
• CMP R
• Complement
• CMA

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Instruction Set Classification
Branching Operations

• Jump
• JMP addr unconditional
• JNZ addr conditional
• CALL
• CALL addr unconditional
• CC addr conditional
• Return
• Restart

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Instruction Set Classification
Machine Control Operations

• Halt, Interrupt, Do nothing
• HLT
• EI
• NOP

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Deeper look at instructions

• MOV R,R
• MOV R,M
• MOV M,R
• MOV M,M (Single Memory Pointer)
• MVI R,imm
• MVI M,imm
• MVI addr,imm (Only via memory pointer)

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Deeper look at instructions

• LXI B, 16-bit imm. BC16-bit imm.
• LXI D, 16-bit imm. DE16-bit imm.
• LXI H, 16-bit imm. HL16-bit imm.
• LXI SP,16-bit imm. SP16-bit imm.
• LHLD 16-bit imm. HL16-bit imm.
• SHLD 16-bit imm. 16-bit imm.HL

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Deeper look at instructions

• LDA 16-bit addr
• LDAX B (BC)
• LDAX D (DE)
• LDAX H (HL) (Already have MOV A,M)
• STA 16-bit addr
• ..
• STAX H (Already have MOV M,A)

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Deeper look at instructions

• INR/DCR R RR1, CY not altered
• INR/DCR M HLHL 1, H nor L altered
• INX/DCX Rp RpRp 1, no flags altered
• DAD Rp HLHLRp only CY affected
• DAA Decimal Adjust not Conversion

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Deeper look at instructions

• ADD R AAR
• ADC R AARCY
• ADD M AAHL
• ADC M AAHLCY
• ADI imm. AA 8-bit imm.
• ACI imm AAimm.CY
• SUB R AA-R
• SBB R AA-R-CY
• SUB M AA-HL
• SBB M AA-HL-CY
• SUI imm. AA- 8-bit imm.
• SBI imm AA-imm.-CY

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Deeper look at instructions

• ANA R AAR
• ANA M AAHLAM
• ANI imm. AA 8-bit imm.
• ORA R AAR
• ORA M AAHLAM
• ORI imm. AA 8-bit imm.
• XRA R AA R
• XRA M AA HLAM
• XRI imm. AA 8-bit imm.

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Deeper look at instructions

• CMA complement accumulator (B,C,D,E..)
• CMC complement carry
• STC set carry
• RLC rotate A left, CY not included
• RRC rotate A rigth, CY not included
• RAL rotate A left through CY
• RAR rotate A right through CY

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Deeper look at instructions
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Deeper look at instructions

• JMP 16-bit addr. PC16-bit addr
• JC/JNC 16-bit addr.
• JZ/JNZ 16-bit addr.
• JM/JP 16-bit addr.
• JPE/JPO 16-bit addr.
• PCHL PCHL
• XCHG DEHL, HLDE not
• XTHL TOSHL, HLTOS

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Deeper look at instructions

• CALL 16-bit addr. PC16-bit addr,push stack
• CC/CNC 16-bit addr.
• CZ/CNZ 16-bit addr.
• CM/CP 16-bit addr.
• CPE/CPO 16-bit addr.

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Deeper look at instructions

• RET PC16-bit addr, pop stack
• RC/RNC
• RZ/RNZ
• RM/RP
• RPE/RPO

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Deeper look at instructions

• Addr
• FF01H 21 LXI H,0100H
• FF02H 00
• FF03H 01
• FF04H 3E MVI A,0C9H
• FF05H C9
• FF06H 2B LOOP DCX H
• FF07H C2 JNZ LOOP
• FF08H 06
• FF09H FF
• FF0AH 76 HLT (RST 7)