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Control Unit (CU)
              Control Unit coordinates and directs the operation of the hardware devices. It also coordinates the  ow and
              execution of the data and instructions that are fed into the computer’s memory. CU functions in an FDES
              (Fetch-Decode-Execute-Store) cycle. It fetches the instruction and data from the memory unit & decodes
              them and passes them to the ALU for further processing. It also directs the ALU to execute the instruction and
              perform the required operations on the data.


              Memory Unit (MU)
              Memory Unit or main storage stores the data, instructions, intermediate results and final results that are ready
              for the output. All instructions or data are stored in the memory unit before being used by the ALU or the CU.
              The main storage is divided into a number of storage locations that can be accessed by a unique number or
              address known as the memory address. Within the CPU there are high-speed, special-purpose memory units
              called registers.

              The Control Unit and the internal storage are linked together by sets of parallel electrical conducting lines
              called buses. The buses that carry data are called ‘Data Buses’. To retrieve data from the memory, it is necessary
              to identify the address of data in the main memory. The address is identified by  Address Buses . The buses
              that carry control signals are called ‘Control Buses’.



              Output Devices

              Output is the information obtained after processing the data. The user receives the result through output
              devices. Output can be in the form of soft copy or hard copy. Soft copy refers to the digital copy which lies
              in the storage device whereas hard copy refers to the printed contents on a paper or film. Some common
              output devices are:
                Printer                                               Plotter

               Speaker                                                Monitor
              Printer

              Printer is a common output device that is used for the purpose of printing
              documents. Printer generates a hard copy of data or information.
              Printers are of different types depending upon:

                Quality of  Printing: The quality of output produced by the printer can be measured in units of dpi (dots
                 per inch) which is also termed resolution.
                Speed: The speed of different types of printers varies widely. The speed of a printer is measured in cps
                 (characters per second), ppm (pages per minute) or lpm (lines per minute).

                Printing  Mechanism:  There  are  different types  of  mechanisms  that  are  applied  in  different  types  of
                 printers. Some printers print by striking the printer head on the paper, some print by forming images on
                 the paper, some print by spraying ink, etc.
              Based on the mechanism, printers can be broadly classified into two categories:

               Impact Printer                                         Non-Impact Printer






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