Definition of Data

Demystifying Computers

How They Really Work

Osher Lifelong Learning Institute
University of Illinois, Urbana-Champaign

Definition of Data

"Numbers that represent (in any possible way) something of interest to human beings"

Computers will be useful in any endeavor that can be represented by numbers.

Computers are nearly useless in areas that cannot be reduced to numbers, such as poetry.

Examples:

Money

Usually the only information we care about in money is the amount, a number.

If the currency, such as dollars, euros, pounds, or yen, is important, an arbitrary number code indicating that currency must be included.

Text

Baudot

1870's

Used with telegraph, then used for AP Teletype and Telecommunications for the Deaf

ASCII Encoding

Early 1960's

127 possible characters

Used with all but IBM mainframes, including Apple II

American character set only

ISO-8859-1

Mid 1980's

255 possible characters

Expanded ASCII to most Western European Latin based alphabets

Backward compatible with ASCII

Used in almost all communication where the worldwide Unicode is not needed

Unicode

Early 1990's

Expanded ISO-8859-1 to include almost every language worldwide

Backward compatible with ISO-8859-1 and ASCII

Over 1 million possible characters

Complicated variable length encoding

Audio

CD Quality - measures the sound wave at 44,100 times a second, with a number from 0 to 65535, with two stereo channels

Pictures

Made of dots called "pixels" (picture elements)

Number of dots usually expressed as the height and width of a rectangle in pixels

Usually 4 measurements for each dot, Red, Green, Blue, and Transparency

Each measurements usually is from 0 to 255

"Screen Resolution" is just the height and width of the entire screen in pixels