Note for COMPUTER ARCHITECTURE ORGANISATION - CAO by Bvsagar Alapati

Topics ( 4 )

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UNIT-3 Microprogrammed Control cpe 252: Computer Organization 1

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Micro programmed control unit • Micro programmed control unit uses sequence of micro instructions in micro programming language • It acts as a mid way between h/w and s/w • It generates a set of control signals on basis of control lines • It is easy to design, test and implement • It is flexible to modify cpe 252: Computer Organization 2

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• Micro programmed control unit consists of • Control signals: group of bits(0,1) • Control variables: binary variables specify micro operation. • Control word: string of 1’s & 0’s represent control variable is called control word. • Control memory: It is memory containing control word. • Micro instructions:It contains control word stored in control mempry and it specifies control signals for execution of micro operations • Micro program: It contains sequence of micro instructions. cpe 252: Computer Organization 3

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Control Unit Implementation • Hardwired Memory Instruction code Combinational Logic Circuits Sequence Counter . . Control signals • Microprogrammed Memory CAR: Control Address Register CDR: Control Data Register Instruction code Next Address Generator (sequencer) CA R Control Memory cpe 252: Computer Organization CDR Decoding Circuit . . Control signals 4