Peripheral Devices: Types, Interfaces, and Classifications
Peripheral Devices
1. Types of Peripherals
One of the main functions of an operating system is to control the computer’s peripheral input/output. The operating system sends commands, determines which device needs the processor’s attention, and eliminates potential errors. Peripherals, which manage information, are classified as follows:
- Block Peripherals: These handle information in fixed-size blocks, transferring data to and from memory in block form.
- Character Peripherals: These input data as individual characters, without a specific order, into computer memory.
Each peripheral consists of a mechanical component and one or more electronic components. The operating system accesses information from main memory as electrical impulses and sends it to the various peripheral devices.
The physical devices managed by the OS for transferring information within the computer are classified by their function:
- Storage: Computer memory or auxiliary external memory.
- Interfaces: Enable communication between the user and the operating system.
- Transmission Media: Buses and channels transmit information between the computer’s components.
Other Important Aspects
Other important aspects of peripherals include the controller, the channel, and interrupts. Controllers or adapters are hardware components that manage peripheral usage. They connect the peripheral to the computer’s motherboard. Controllers require driver software to enable communication between the peripheral and the microprocessor. These drivers are designed for various operating systems.
2. User Interfaces
Interfaces facilitate communication between hardware and software through the operating system. They can be classified as:
- Text-based Interfaces: User commands and operating system responses are displayed as character strings. Text-based screens typically have a size of 80 columns by 24 rows.
- Graphical User Interfaces (GUI): Mouse usage is essential in GUIs. Information is displayed in separate windows or screens.
3. Classification of Peripherals
The most common classification of peripherals is:
- Input Devices: Used to enter information into the computer. Data flows from these devices to memory and other internal components for processing.
- Output Devices: Used to extract information from memory and other internal components and display the data.
- Input/Output (I/O) Devices: Used to both input and output data to and from the computer.
External storage peripherals, also known as auxiliary or mass storage, address the limitations of main memory, such as its limited capacity and volatility. These devices store information persistently.
Common I/O Peripherals
Some of the most important I/O peripherals include:
- Keyboard and Mouse: The primary input devices. Keyboards come in various models with different numbers of keys, including general typing keys, function keys, a number block, editing and cursor movement keys, and special keys.
- Monitor: An output device that can be monochrome or color. Its performance depends on the graphics card, memory, refresh rate, and size.
- Printer: An output device that presents information on paper. Common types include impact printers (less common now) and non-impact printers like thermal, inkjet, laser, and electromagnetic printers.
- Scanner: An input device that converts images or text into digital data.
- Modem/Router: An I/O device that connects to a phone line and enables remote communication with other computers.
- Hard Drives: High-capacity, high-speed storage devices used for installing operating systems and software applications.
- Digitizing Tablet and Stylus: Input devices used for creating charts and diagrams.
- CD-ROM: An input device that accesses information using laser technology.
- DVD (Digital Versatile Disc): Similar to CD-ROMs but with much greater storage capacity.