Text D: Input and Output Devices

Data are entered into the computer and the processed data made available via input/output devices. I/O devices are the means by which a computer exchanges information with the outside world. Placing data into the computer system requires converting it from human-readable to machine-readable data. Data is thus placed in a computer system in a two-stage process: data entry converts human-readable data into machine-readable form; data input then transfers it to the computer.

Devices that provide input to or output of the computer are called peripherals. The most common peripheral devices used for entry and input of data such as characters, text, and basic commands include a keyboard and a computer mouse and output devices such as a display and printer. Scanners are input devices that convert images and text into binary digits. Terminals perform data entry and data input at the same time. They transfer the data to the processing section of the computer system. Point-of-sale (POS) devices are terminals with scanners that read and enter codes into computer systems. Voice-recognition devices can recognize human speech. Source data automation involves automating data entry and input so that data is captured close to its source and in a form that can be input correctly to the computer. Automated teller machines (ATMs) are terminals with keyboards used for transactions. Touch-sensitive screens can function both as input and output devices.

Output devices provide information in different forms, from hard copy to sound in digital format. Display monitors are standard output devices; monitor quality is determined by size, color, and resolution. Display monitors can be in the form of CRT, LCD, plasma and LED monitors. Other output devices include printers, plotters, speakers, etc. Printers are popular hard-copy output devices whose quality is measured by speed and resolution. All auxiliary (secondary) storage devices are used as input/output devices. Computer networking is another form of I/O. In fact, I/O devices are often complex computers, with their own CPU and memory.

Agree or disagree with the following statement.

1. Data is entered into the computer and the processed data is made available via input/output devices. 2. A keyboard is a device used for entry and input images. 3. Scanners convert images and text into sound in digital format. 4. The CPU is a peripheral device. 5. To make data available to humans the computer converts it into machine-readable form.

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