Tech Guide 1
Hardware
TG1.1 Components of a Computer System
TG1.2 Evolution of Computer Hardware
TG1.3 Types of Computers
TG1.4 Microprocessor and Primary Storage
TG1.5 Input/Output Devices
TG1.1 Components of a Computer System
Computer hardware is composed of the following components: central processing unit (CPU), primary storage, secondary storage, input devices, output devices, and communication devices. Communication devices are covered in detail in Tech Guide 4.
The input devices accept data and instructions and convert them to a form that the computer can understand. The output devices present data in a form people can understand. The CPU manipulates the data and controls the tasks done by the other components. Primary storage (internal storage that is part of the CPU) temporarily stores data and program instructions during processing. Secondary storage (external storage such as flash drives) stores data and programs that have been saved for future use. Communication devices manage the flow of data from public networks (e.g., Internet, intranets) to the CPU, and from the CPU to networks. A schematic view of a computer system is shown in Figure TG1.1.
REPRESENTING DATA, PICTURES, TIME, AND SIZE IN A COMPUTER
ASCII. Computers are based on integrated circuits (chips), each of which includes millions of sub-miniature transistors that are interconnected on a small (less than l-inch-square) chip area. Each transistor can be in either an “on” or an “off” position.
The “on-off” states of the transistors are used to establish a binary 1 or 0 for storing one binary digit, or bit. A fixed number of bits representing specific characters—letters, numbers, and special symbols—is known as a byte, usually 8 bits. Because a bit has only two states, 0 or 1, the bits comprising a byte can represent any of 28, or 256, unique characters.
The character that the byte