Ch 2. Key Terms

ASCII (American Standard Code for Information Interchange): One of the earliest and most widely adopted character encoding standards; each character is assigned a 7-bit integer (128 unique codes), including letters, digits, punctuation, symbols, and control characters.

Character Encoding Systems: Assign numeric codes to each character so computers can process letters, digits, punctuation marks, and control symbols.

Denormalized Numbers: Used in IEEE 754 to fill the gap between the smallest normalized number and zero; they set all exponent bits to 0 and use a mantissa representing a fraction less than 1.0.

EBCDIC (Extended Binary Coded Decimal Interchange Code): An 8-bit character encoding system developed by IBM and used on mainframe and midrange systems; supports 256 characters and is incompatible with ASCII.

FloatingPoint Representation: Approximates real numbers (very large and very small, with fractional components) using sign bit, exponent (scales the number), and mantissa (significant digits), typically per IEEE 754 single and double-precision formats.

One’s Complement: Negative numbers are represented by inverting all bits of the corresponding positive number; they have two representations for zero.

Overflow: Occurs when the result of a computation is above the maximum value that can be represented with the given number of bits.

Signmagnitude: The most significant bit (MSB) indicates the sign—0 for positive and 1 for negative; simple, but has two representations for zero, complicating arithmetic.

Two’s Complement: Negative numbers are represented by inverting the positive number and adding 1; the most widely used method in modern computing, with a single representation for zero and simplified arithmetic.

Underflow: Occurs when a number is too small (in magnitude) to be represented in the chosen format, especially in floating-point arithmetic.

Unicode: A universal standard that supports over 150,000 characters and is backward compatible with ASCII; commonly encoded as UTF-8 (1 to 4 bytes), UTF-16 (2 to 4 bytes), or UTF-32 (4 bytes).

Unsigned integer: Uses bits to represent values starting from 0 up to a maximum determined by the number of bits.