Computer Awareness Quiz: Hardware: Input and Output Devices

A touchscreen accepts a finger tap or a stylus stroke as input and displays the result on the very same surface, so the one piece of hardware performs both jobs.

He built the first mouse, a small wooden box with a pair of wheels underneath, at the Stanford Research Institute, and the patent describes it as an X-Y position indicator for a display system.

Its print head carries a column of tiny pins that strike an inked ribbon against the paper, forming each character out of dots.

MICR stands for Magnetic Ink Character Recognition. The line of characters printed along the foot of a cheque is set in magnetic ink in the E-13B font, and the reader identifies each character from its magnetic signal, so the cheque is sorted correctly even when it has been folded, stamped…

The word is a contraction of picture element. A screen image is a grid of these points, and the number of them across and down the screen is what is quoted as the resolution of the monitor, so a higher pixel count means a finer picture.

Print quality depends on how many separate dots of ink or toner the printer can place in one inch of paper, so a printer working at a higher DPI produces smoother curves and crisper small text.

A plain scan is only a picture of the page, and nothing in it can be searched or corrected. OCR examines the shape of every character in that picture, matches it against the letters it knows and hands back real text that can be edited in a word processor.

A plotter holds a pen against the paper and moves it, so it draws continuous lines rather than building the image out of dots.

It builds the image of a whole page on a photosensitive drum with a laser beam, then picks up dry toner on that image and fuses it onto the paper with heat and pressure.

A plotter takes a drawing that the computer has already prepared and puts it on paper with a moving pen, so data travels out of the machine and never into it.

A line printer, such as a drum or chain printer, sets up and prints a whole line of characters at one stroke, so counting the lines it finishes in a minute is the natural measure of its speed.

The device does two opposite jobs, and the name simply joins them. While sending, it modulates: it converts the digital signal of the computer into an analogue signal that an ordinary line can carry.