MPMC Microprocessor

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<ul><li> 1. ARCHITECTURE OF 8086MICROPROCESSORByA.S.Krishna</li></ul> <p> 2. What is a Microprocessor ?A microprocessor incorporates the functions of acomputer's central processing unit (CPU) on a singleintegrated circuit (IC), or at most a few integratedcircuits.The microprocessor is a multipurpose, programmabledevice that accepts digital data as input, processes itaccording to instructions stored in its memory, andprovides results as output. It has internal memory.Microprocessors operate on numbers and symbolsrepresented in the binary numeral system. 3. What is 8086 Microprocessor ?The 8086 is also called iAPX 86. It is a 16-bitmicroprocessor chip designed by Intel between early1976 and mid-1978, when it was released.It is notable as the processor used in the original IBMPC. 4. Architecture of an 8086MicroprocessorThe architecture of 8086 provides a number ofimprovements over 8085 architecture.It supports a 16-bit ALU, a set of 16-bit registersand provides segmented memory addressingcapability, a rich instruction set, powerful interruptstructure, fetched instruction queue for overlappedfetching and execution etc., 5. Bus Interface Unit (BIU)In the BIU we have some collection components. Theyare:-1. Address Adder.2. Segment Registers and Program Counter.3. Instruction Queue 6. 1. Address AdderIn the address adder the adder addsthe addresses and transfer them to thememory though the internal data buspath. 7. 2. Segment Registers andProgram CounterSegment RegistersCode segmentData segmentStack segmentExtra segmentSegment RegistersCSDSSSESProgram CounterIPProgram CounterInstruction Pointer 8. 3. Instruction QueueInstruction Queue654321This a Queue which canstore the given instructionsone-by-one. 9. Execution Unit(EU)In the EU we have some collection components.They are:- 1. General Registers.2. Execution Unit Control System.3. ALU4. Operands and Flags. 10. 1. General Registers In this we have two types of registers.They are:- 1. Main Registers.2. Index Registers.Main RegistersAH AL AX(Primary accumulator)BH BL BX(Base accumulator)CH CL CX(Counter accumulator)DH DL DX(accumulator otherfuntions) 11. Index RegistersSP Stack PointerBP Base PointerSI Source IndexDI Destination Index 12. 2. Execution Unit Control SystemIn this unit the Execution is controlled and istransferred to the all other components through theinternal data bus.3. ALU(Arithmetic Logical Unit)Here all the ALU operation are performed andtransferred the data through the internal data bus. 13. 4.Flags RegistersThis flag is identical to 8085 flag register, with anadditional overflow flag, which is not present in 8085.The 8086 has a 16-bit flag register which is divided intotwo parts, viz.(a) condition code (or) status flags and (b)machine control flags.The condition code flag register is the lower byte of the16-bit flag register along with the overflow flag. The machine control flag register is the higher byte ofthe flag register of 8086 which contains three flags, viz.direction flag(D), interrupt flag(I) and trap flag(T). 14. The bit configuration of 8086 flagregister.15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0X X X X O D I T S Z X Ac X P X CyO Overflow flagD Direction flagI Interrupt flagT Trap flagS Sign flagZ Zero flagAc Auxillary carry flagP Parity flagCy Carry flagX Not used (or) Future use 15. Memory Address and data bus interfaceAddress/StatusA16/S3Address/DataAD0/AD15Instruction Queue (6 bytes)Decoding circuitTiming and control circuitClock and control signalsAddress AdderCSDSSSESIPALU (16)FLAGS (16)15 0AH ALBH BLCH CLDH DLIPIPIPIPAXBXCXDXRegister BankBIUEU 16. Pin Diagram of8086Microprocessor</p>