I NSTRU C TI O N SET, MAC HI NE C O DE A ND ADD RESSI NG M ODE MNEMONICS, OPCODES AND ASSEMBLER LANGUAGES
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I NSTRUCTI ON SET,M ACH I NE CODE AND
ADDRESSI NG M ODEMNEM ONI CS, OPCODES ANDASSEM BLER LANGUAGES
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THE INSTRUCTION SET OF THE 8088/8086Data tr ansfer
instructionArithmeticinstruction
Logicinstruction
• t ransfers data
between memoryand registerswithin themicroprocessor orbetween int ernalregisters• ex: MOVinstruction
• performs
addition,subtraction,multiplication,divi sion, compareand othermathematicaloperations• ex: ADDinstruction
• performs logic
instructionsincluding AND,OR and XORinstructions• ex: RCLinstruction
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THE INSTRUCTION SET OF THE 8088/8086Stringmanipulation
instruction
Controltransfer
instruction
Processorcontrol
instruction
• for al l thisinst ruct ion thememory source isDS:DI and thememory
dest inati on isES:DI• ex: CMPSinstruction
• decision makinggroup where adecision dependson a previousresul t such as a
mathematicaloutcome• ex: INTinstruction
• used to controlthe operat ion ofthe processor andset or clear thestatus indicators
• ex: HLTinstruction
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SOFTWARE (INSTRUCTION)Op-code
ident i fies the operat ion t hat is to beperformed
Operand
the data that are to be processed
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SOFTWARE (MACHINE CODE)
AddressOp-code
andoperand
Label Mnemonic Comments
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SOFTWARE (MACHINE CODE)Address
Op-code andoperand
Label M nemonic Comments
Location ofthe op-code
and relateddata.
Hex code forinstruction
and relatedhex data.
A referencepoint given
a name tohelp relatethe programto a flowchart.
Manufacturers
mnemonicfor thatinstruction.
Anything tohelp
understandhow theprogramworks. Thesemicolonidentifiesthe start ofa comment .
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ADDRESSING MODE 8088/8086Addressing mode:
Used to descr ibe the way a part icularinst ruct ion lets the microprocessorknow where the source or dest inat ion islocated
Method of speci fying an operand
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ADDRESSING MODE 8088/8086The addressing modes are categor ized into
three types:
1. Register addressing mode
2. Immediate addressing mode
3. Memory addressing mode
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ADDRESSING MODE 8088/8086Five memory addressing mode:
1. Di rect addressing mode
2.Register indi rect addressing mode
3. Based addressing mode
4. Indexed addressing mode
5. Based-indexed addressing mode
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ADDRESSING MODE 8088/8086Register Addressing Mode
Register addressing is an addressingmode where the sour ce and thedest inat ion are both register .
Ex: M OV DS, AX ;copy AX int o DS
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ADDRESSING MODE 8088/8086 Immediate Addressing Mode
Immediate addressing is the addressingmode where the requi red data(operand)is par t of t he inst ruct ion.
Ex: M OV AX, 1000H ;load AX wi th1000H
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ADDRESSING MODE 8088/8086Di rect Addressing Mode
Di rect (absolut e, extended etc) is anaddressing mode where the operandspecifi es the sour ce or the dest inat ion.
Ex: M OV CX, [1234H ] ;move cont ent in1234H into CX
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ADDRESSING MODE 8088/8086Register I ndirect Addressing Mode
Stor ing the memory address in apoint er or index register (SP,BP,SI ,orDI).
Ex: M OV [SI ],00FFH ;load data 00FFinto address that stored in SI
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ADDRESSING MODE 8088/8086Based Addressing Mode
The effect ive address of the operand isobtained by adding a direct or indi rect
displacement to the cont ent s of ei therbase register BX or base point erregister BP
Ex: M OV [BX] + 1243H , AL
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ADDRESSING MODE 8088/8086 I ndexed Addressing Mode
Use the value of displacement as apointer to the star t ing point of an array
of data in memory and t he cont ent s ofthe speci fied register as an index thatselect speci fi c element in t he array thatis to be accessed.
Ex: M OV AL, [SI ] + 2000H
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ADDRESSING MODE 8088/8086Based-Indexed Addressing Mode
Use to access complex data st ructuressuch as two-dimensional array
Ex: M OV AH , [BX] [SI ] + 1234H