Components Of Computer unit-2

Components Of Computer unit-2

• 1.
  Components of ComputerThe components can be classified into two broad categories as : Hardware Software Hardware Hardware refers to any physical component of a computer. For example, CPU, Monitor, Keyboard, Hard Disk, Floppy Disk, Printer, etc. Are physical components and thus, is hardware. Software Software refers to the programs, which are required to operate the computer. In other words, we can describe software as the logical entity, which enables the physical entities (hardware) to function properly. “ A set of programs is also called as Software.”
• 2.
  Organization of ComputerA computer system has the following main components - · Input Unit/Devices · Output Unit/Devices · Central Processing Unit · Memory Unit/Storage Devices
• 3.
  Central Processing UnitCentral Processing Unit (CPU) is the main component or “brain” of a computer, which performs all the processing of input data. Its function is to fetch, examine and then execute the instructions stored in the main memory of a computer. In microcomputers, the CPU is built on a single chip or integrated Circuit (IC) and is called as a Microprocessor. The CPU consists of the following distinct parts: · Arithmetic Logic Unit (ALU) · Control Unit (CU) · Registers · Buses · Clock
• 4.
  Arithmetic Logic UnitThe arithmetic and logic unit of CPU is responsible for all arithmetic operations like addition, subtraction, multiplication and division as well as logical operations such as less than, equal to and greater than. Actually, all calculations and comparisons are performed in the arithmetic logic unit.
• 5.
  Control Unit Thecontrol unit is responsible for controlling the transfer of data and instructions among other units of a Computer. It is considered as the “Central Nervous System” of computer, as it manages and coordinates all the units of the computer. It obtains the instructions from the memory, interprets them and directs the operation of the computer. It also performs the physical data transfer between memory and the peripheral device.
• 6.
  Registers Registers aresmall high-speed circuits (memory locations), which are used to store data, instructions and memory addresses (memory location numbers), when ALU performs arithmetic and logical operations. Registers can store one word of data (1 word = 2 bytes & 1 byte = 8 bits. Depending on the processor’s capability, the number and type of registers vary from one CPU to another. Registers can be divided into six categories viz. General Purpose Registers, Pointer Registers, Segment Registers, Index Registers, Flags Register and Instruction Pointer Register, depending upon their functions.
• 7.
  Buses Data isstored as a unit of eight bits (BIT stands for Binary Digit i.e. 0 or 1) in a register. Each bit is transferred from one register to another by means of a separate wire. This group of eight wires, which is used as a common way to transfer data between registers, is known as a bus . It is actually a connection between two components to transmit signal between them. Bus can be of three major types viz. Data Bus, Control Bus and Address Bus. The data bus is used to move data, address bus to move address or memory location and control bus to send control signals between various components of a computer.
• 8.
  Clock Clock isanother important component of CPU, which measures and allocates a fixed time slot for processing each and every micro-operation (smallest functional operation). COMPUTER AWARENESS FOR Central Processing Unit (CPU) is the main component or “brain” of a computer, which performs all the processing of input data. Its function is to fetch, examine and then execute the instructions stored in the main memory of a computer. In microcomputers, the CPU is built on a single chip or integrated Circuit (IC) and is called as a Microprocessor. The CPU consists of the following distinct parts: · Arithmetic Logic Unit (ALU) · Control Unit (CU) · Registers simple terms, CPU is allocated one or more clock cycles to complete a micro-operation. CPU executes the instructions in synchronization with the clock pulse. The clock speed of CPU is measured in terms of Mega Hertz (MHz) or Millions of Cycles per second. The clock speed of CPU varies from one model to another in the range 4.77 MHz (in 8088 processor) to 266 MHz (in Pentium II). CPU speed is also specified in terms of Millions of instructions Per Second (MIPS) or Million of Floating Point Operations Per Second (MFLOPS). Now these days we have clock speeds of CPU which in Gigahertz. E.g. we have Pentium IV having a clock speed of 3.04GHz, or AMD Athlon having speed of 2.7GHz.
• 9.
  Storage Unit /Memory Unit Memory Unit is that component of a computer system, which is used to store the data, instructions and information before, during and after the processing by ALU. It is actually a work area (physically a collection of integrated circuits) within the computer, where the CPU stores the data and instructions. It is also known as a Main/Primary/internal Memory. Storage unit also consist of storage devices, which stores the data on permanent basis. I.e. unless or until we want to delete the data by ourselves the data will be available even if the power goes off. Hard disks, Compact Disks, Floppy disks are the examples of secondary storage devices.