3. Definitions Flashcards
Arithmetic Logic Unit (ALU)
Hardware that performs addition, subtraction, and usually logical operations such as AND and OR.
dividend
A number being divided.
divisor
A number that the dividend is divided by.
quotient
The primary result of a division; a number that when multiplied by the divisor and added to the remainder produces the dividend.
remainder
The secondary result of a division; a number that when added to the product of the quotient and the divisor produces the dividend.
scientific notation
A notation that renders numbers with a single digit to the left of the decimal point.
normalized
A number in floating-point notation that has no leading 0s.
floating point
Computer arithmetic that represents numbers in which the binary point is not fixed.
fraction
The value, generally between 0 and 1, placed in the fraction field. The fraction is also called the mantissa.
exponent
In the numerical representation system of floating-point arithmetic, the value that is placed in the exponent field.
overflow (floating-point)
A situation in which a positive exponent becomes too large to fit in the exponent field.
underflow (floating-point)
A situation in which a negative exponent becomes too large to fit in the exponent field.
double precision
A floating-point value represented in a 64-bit doubleword.
single precision
A floating-point value represented in a 32-bit word.
exception. Also called interrupt.
An unscheduled event that disrupts program execution; used to detect overflow.
interrupt
An exception that comes from outside of the processor. (Some architectures use the term interrupt for all exceptions.)
guard
The first of two extra bits kept on the right during intermediate calculations of floating-point numbers; used to improve rounding accuracy
round
Method to make the intermediate floating-point result fit the floating-point format; the goal is typically to find the nearest number that can be represented in the format. It is also the name of the second of two extra bits kept on the right during intermediate floating-point calculations, which improves rounding accuracy.
units in the last place (ulp)
The number of bits in error in the least significant bits of the significand between the actual number and the number that can be represented.
sticky bit
A bit used in rounding in addition to guard and round that is set whenever there are nonzero bits to the right of the round bit.
fused multiply add
A floating-point instruction that performs both a multiply and an add, but rounds only once after the add.
