Elementary Statistics and Computer Application

Components of CPU

The computer system essentially comprises three important parts – input device,

• central processing unit (CPU) and the output device. The CPU itself is made up of many components. Among the various components the three important components namely, the arithmetic logic unit (ALU), memory unit, and the control unit are important. In addition to these, auxiliary storage/secondary storage devices are used to store data and instructions on a long-term basis.


Arithmetic logic unit

• An arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit (CPU) of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers.


The Memory unit is linked with other parts of the computer



• Computer’s memory can be classified into two types – RAM and ROM.
• RAM or Random Access Memory is the central storage unit in a computer system. It is the place in a computer where the operating system, application programs and the data in current use are kept temporarily so that they can be accessed by the computer’s processor. The more RAM a computer has, the more data a computer can manipulate. This memory is also known as user memory.


• Random access memory, also called the Read/Write memory, is the temporary memory of a computer. It is said to be ‘volatile’ since its contents are accessible only as long as the computer is on. The contents of RAM are cleared once the computer is turned off.
  


• ROM or Read Only Memory is a special type of memory which can only be read and contents of which are not lost even when the computer is switched off. It typically contains manufacturer’s instructions. Among other things, ROM also stores an initial
• program called the ‘bootstrap loader’ whose function is to start the computer software operating, once the power is turned on.
• Read-only memories can be manufacturer-programmed or user-programmed. While manufacturer-programmed ROMs have data burnt into the circuitry, user programmed.


• ROMs can have the user load and then store read-only programs. PROM or Programmable ROM is the name given to such ROMs. Input devices allows the user to enter the program and data and send it to the processing unit. The common input devices are keyboard, mouse and scanners. Output devices show the processed data – information – the result of processing. The devices are normally a monitor and printers