An Overview of the Computer System
This lesson includes the following sections:
• The Parts of a Computer System
• Looking Inside the Machine
• Software: Bringing the Machine to Life
The Parts of a Computer System
• What is a Computer?
The Parts of a Computer System - What is a Computer?
• A computer is an electronic device used to process data.
• A computer can convert data into information that is useful to people.
• A complete computer system includes four distinct parts:
The Parts of a Computer System - Hardware
• A computer's hardware consists of electronic devices; the parts you can see and touch.
• The term "device" refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, etc.
The Parts of a Computer System - Software
• Software – also called programs – consists of organized sets of instructions for controlling the computer.
• Some programs exist for the computer's use, to help it manage its own tasks and devices.
• Other programs exist for the user, and enable the computer to perform tasks for you, such as creating documents.
The Parts of a Computer System - Data
• Data consists of raw facts, which the computer can manipulate and process into information that is useful to people.
• Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as numbers.
• Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images.
The Parts of a Computer System – Users
• People are the computer's operators, or users.
• Some types of computers can operate without much intervention from people, but personal computers are designed specifically for use by people.
Looking Inside the Machine
• Types of Hardware
• The CPU
• How Memory is Measured
• Input and Output Devices
• Storage Devices
Looking Inside the Machine – Types of Hardware
A computer's hardware devices are categorized as follows:
• Input and output (I/O) devices
• Storage devices
Looking Inside the Machine - The CPU
The procedure that transforms raw data into useful information is called processing. This function is divided between the computer's processor and memory.
The processor is also called the central processing unit (CPU). It manages all devices and performs the actual processing of data.
The CPU consists of one or more chips attached to the computer's main circuit board (the motherboard).
Looking Inside the Machine - Memory
• Memory also consists of chips attached to the motherboard.
• Memory holds data and program instructions as the CPU works with them. This memory is called Random Access Memory (RAM).
• The CPU can find any piece of data in RAM, when it needs it for processing.
• RAM is volatile, meaning it holds data only when the power is on. When the power is off, RAM's contents are lost.
Looking Inside the Machine – How Memory is Measured
• The smallest usable unit of measure for memory is the byte – the amount of memory required to hold one character, like the letter A or the numeral 2.
• Computers work with larger chunks of data, measured in multiple bytes, as shown below:
UnitApprox. Value (Bytes) Actual Value (Bytes)
Kilobyte (KB)1,000 1,024