L8 CU - Computer Science 230H CU Control Unit Prepared by...

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Computer Science 230H CU – Control Unit Prepared by Michael Jack Fall 2007
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ALU 2 References The information and figures for the following slides were prepared from the following source: Patterson, D., and Hennessy J., Computer Organization and Design, 3rd edition, 2005 Stallings, W., Computer Organization and Architecture: Designing for Performance 7 th edition, 2006 Hircock B., Computer Science 230 Course Notes
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ALU 3 The job of a Control Unit (CU) is to cause things happen! – It is essentially an engine that runs the entire computer Each instruction cycle consists of a set of micro-operations that generate control signals. CU has two basic responsibilities: – Cause processor to execute micro-operations in the proper sequence. – Generate control signals to cause each micro-operation be executed. CU issues control signals: – To the processor to cause data exchange with memory and I/O modules. – To the processor to move data between registers. – To cause the ALU to perform a specified function – To regulate other internal operations. Input to the CU consists of: – Instruction register – Flags – Control signals from external sources (e.g. interrupts) Introduction
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ALU 4 The execution of a program consists of the sequential execution of instructions – Each instruction is executed during an instruction cycle made up of shorter subcycles (e.g. fetch, indirect, execute, interrupt.) – The performance of each subcycle involves one or more shorter operations – micro-ops. Micro-Operations
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ALU 5 Memory address register (MAR): – Connects directly to the address bus. – Specifies the address in memory for a read or write operation. Memory data/buffer register (MBR) – Connects directly to the data bus. – Contains the value to be stored
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This note was uploaded on 02/14/2010 for the course COMPUTER S COIS-3030 taught by Professor Hircock during the Spring '10 term at Trent University.

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L8 CU - Computer Science 230H CU Control Unit Prepared by...

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