Class 6 -Revision 2

CENTRAL PROCESSING UNIT (CPU)

• Also called Microprocessor
• Brain of the Computer
• Speed of the Computer depends upon the Microprocessor
• Dual core, i3, i5, i7 are the examples
• Consists of 3 parts

   1. Arithmetic Logic Unit (ALU)

• All mathematical Calculations, logical comparisons are done

   2. Registers

• Small memory units
• Stores data, instructions and results while processing

   3. Control Unit (CU)

•  Controls the movement of  data inside and outside the CPU
• Communicates between the Registers and the ALU
• Communicates between the CPU and the Input-Output  storage devices.

OUTPUT DEVICES
   1. Monitor

• The screen comprises of tiny dots known as pixels
• Pixels combine to form an image

            Types of Monitors
             A.Cathode Ray Tube (CRT)
                 - Bulky 
                 - Needs more power
                 - Cheaper
             B. Liquid Crystal Display (LCD)
                 - Uses TFT (Thin Film Transmitter) technology
                 - Light weight and compact
                 - Needs less power
                 - Expensive
   2. Printers
        i. Impact printer                
            - It physically strikes a head or a needle against an ink 
               ribbon to make a mark on the paper. Low quality printout,
               takes more time.
             
              Line Printer - It prints single line at a time   
              Character Printer  - It prints single character at a time
                 
               Dot Matrix Printer
                  - Prints one character at a time            
                  - Speed is measured in characters per second (cps)
                  - Inexpensive
                  - Very noisy
                  - Low quality printout
                  - Print only in black
                  - Takes more time
               Daisy Wheel Printer
                  - Cannot print graphics
                  - Slow and more expensive than Dot Matrix Printer
                Drum Printers
                  - Faster than the above two printers
                  - Prints a line in a single operation
                  - Low quality printout
                  - Loud and
                  - very expensive

        ii. Non impact printer
             - These printers do not involve any contact between the
                print head and the surface. High speed and high quality.
          
               Ink Jet Printer
                  - High resolution
                  - High quality and text
                  - Sprays droplets of ink onto the paper to produce a        
                       Character
                 -Thermal heating process or the Bubble inkjet 
                        technology is used

                Laser Printer
                  - Good quality printout
                  - High speed
                  - Expensive
                          - High Maintenance Cost

   3. Plotter

• Generates graphical outputs such as images, charts, graphs, blueprints, maps, circuit diagrams and other line-based diagrams.
• Draws lines using a pen.
• Used by engineers and architects.