## Tuesday, July 27, 2010

### Today's word is Boolean

This is the logic that computers use to determine if a statement is true or false. There are 4 main boolean operators: AND, NOT, OR, and XOR. Below are some examples of how the 4 operators work:

x AND y retuns True if both x and y are true, otherwise the expression returns False.

NOT x returns True if x is false (or null) and False if x is true.

x OR y returns True if either x or y or both are true; only if they are both false will it return False.

x XOR y returns True if either x or y are true, but not both. If x and y are both true or false, the statement will return False.

While boolean expressions are what drive the CPUs in computers, they can also be used by computer users. For example, when searching for information on the Web, many search engines accept boolean operators in the search phrases (i.e. "Yamaha AND piano NOT motorcycle"). Programmers often use boolean expressions in software development to control loops and variables as well.

### Today's word is ASCII (American Standard Code for Information Interchange)

Stands for "American Standard Code for Information Interchange." ASCII is the universal standard for the numerical codes computers use to represent all upper and lower-case letters, numbers, and puctuation. Without ASCII, each type of computer would use a different way of representing letters and numbers, causing major chaos for computer programmers (allowing them even less sleep than they already get).

ASCII makes is possible for text to be represented the same way on a Dell Dimension in Minneapolis, Minnesota as it is on an Apple Power Mac in Paris, France. There are 128 standard ASCII codes, each of which can be represented by a 7 digit binary number (because 2^7 = 128).