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Processor and Primary Memory of Computer


CPUThe CPU and Primary Storage


          The CPU is the part of the computer system where the manipulation of symbols, numbers, and letters occurs, and it controls the other parts of the computer system.




Processor

Processor

CPU and Primary Storage

          Three kinds of busses linked between the CPU, primary storage and the other devices in the computer system:
         Data bus
          Pass information in bi-directional. 
         Address bus
          Transmits signals for locating a given address in primary storage, indicating where data should be placed.
         Control bus
          Transmits signal specifying whether to read or write data to or from primary storage address, input device or output device.
          The characteristics of the CPU and primary storage are very important in determining a computer’s speed and capabilities


The Arithmetic-Logic Unit and Control Unit  


          An arithmetic logic unit (ALU) and control unit is one of the core components of all central processing units.
          The ALU performs the computer’s principal logical and arithmetic operations.
          It adds, subtracts, multiples, and divides, determining whether a number is positive, negative, or zero.
          ALU must be able to determine when one quantity is greater than or less than another and when two quantities are equal.
          The control unit coordinates and controls the other parts of the computer system.
          It reads a stored program, one instruction at a time and directs other components of the computer system to perform the program’s required tasks.

Processor


          Which processor should you select?
          The faster the processor, the more expensive the computer

IC  CPU


Primary Storage


          Primary storage is a category of computer storage, often called main memory.
          Has three functions:
         Stores all or part of the program that is being executed.
         Stores the operating system programs that manage the operation of the computer.
         Holds data that the program is using.
          Data and program are placed in primary storage before processing, between processing steps and after processing has ended prior to being returned to secondary storage or released as output.

Memory


          How is memory measured?
          By number of bytes available for storage


Memory


          Modern primary storage devices include:

         Random access memory (RAM)

          is used for short-term storage of data or program instructions. RAM is volatile. Its contents will be lost when the computer’s electric supply is disrupted by a power outage or when the computer turned off.

         Read-only memory (ROM)

          can only be read from. It cannot be written to. ROM chips come from the manufacturer with programs already burned in, or stored. ROM is used in general-purpose computers to store important or frequently used programs, such as computing routine for calculating the square roots of numbers.




RAM

Working Of RAM





Types Of RAM


ROM

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