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Module I. Overview of Computer Architecture and Organization. Structure of IAS Computer. UQ: Explain the role of different registers like IR,PC, SP ,AC,MAR,MDR used in Von Neumann Model [5]. Functions of different registers. Memory Buffer Register (MBR) (Data Register)
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Module I Overview of Computer Architecture and Organization
UQ: Explain the role of different registers like IR,PC,SP,AC,MAR,MDR used in Von Neumann Model [5]
Functions of different registers • Memory Buffer Register (MBR) (Data Register) • Store any 40-bit word • Used to store operand of an instruction • It contains a word to be stored in memory or sent to I/O unit or it is used to receive a word from memory or I/O unit
Functions of different registers • Memory Address Register(MAR)/ Address Register(AR) • 12 bit register • Specify the address of the memory location to be written into or read from MBR
Functions of different registers • Instruction Register(IR) • Holds the opcode of currently executing instruction • Instruction Buffer Register(IBR) • Since 2 instructions are fetched simultaneously, the opcode of the second instruction is stored in IBR • Program Counter(PC) • Store address of the next instruction pair to be executed • Also referred as Instruction Address Register
Functions of different registers • Accumulator (AC) and Multiplier Quotient (MQ) • 40 bit register • Used for the temporary storage of operands and results of the ALU operation • E.g. result of multiplication of two 40 bit numbers are stored as Most Significant : AC Least Significant : MQ
Instruction Cycle of IAS • It consist • Fetch Cycle • Execute Cycle
Fetch Cycle • Opcode of next instruction is loaded into IR and address portion into MAR • This instruction may be taken from IBR or loaded from memory by loading a word into the MBR and then down to IBR,IR and MAR.
Execute Cycle • Once opcode reaches IR execution begins • Control circuitry interprets opcode and executes instruction using control signals and ALU
Quiz • Which is not a function of computer ? • Data Processing • Data Packing • Data Storage • Data Movement
Quiz • Which is not a structural component of computer ? • CPU • Main Memory • Operating System • System Interconnections
Quiz • Which is the first type of Programming Language ? • Assembly Level • Machine Level • High Level
Quiz • ENIAC stands for • Electronic Numeric Integrator and Computer • Electronic Numeric Integrator and Calculator • Electric Numeric Integrator and Computer • Electric Numeric Integrator and Calculator
Clock Speed • Operations of Processor is governed by System clock • Speed of the processor is dictated by pulse frequency of clock • Clock signals are generated by a quartz crystal which generates a constant signal wave when power is applied. This wave is converted to digital voltage and is given to processor
Clock Speed • Rate of pulses is clock rate or clock speed • One increment of clock is clock cycle • Time between pulses is cycle time • Multiple instructions may get executed simultaneously, hence clock speed alone cannot define performance