AP Computer Science A

accessor method

a method that accesses an object but does not change it
actual parameter - the expression supplied for a formal parameter of a method by the caller

address

a location in memory at which a binary number (usually a byte, or value of 8 bits) is stored. The location in memory can itself be identified by a binary number - this number, the absolute or explicit address, gives the absolute location of the address in memory, while a relative address specifies a location memory (some other address only in relation to the current, or base, address. All access to memory is access to to a cell of memory found at a specified address.

algorithm

a well-ordered collection of unambiguous and effectively computable operations that, when executed, produces a result and halts in a finite amount of time
[[an unambiguous, executable, and terminating specification of a way to solve a problem

argument

an actual parameter in a method call, or one of the values combined by an operator]]
arithmetic/Logic Unit (ALU)

ASCII

The American Standard Code for Information Exchange - a character-encoding scheme based on the English alphabet used to represent text in computers. It uses 8 bits to represent each character, so it is able to encode a total of 2^8 = 256 different characters. These are assigned the integer values 0 to 255. Only 32 to 126 have been assigned to printable characters. The ASCII has been largely supplanted by UNICODE and the UCS (universal character set), which are backwards compatible with it (commonly encoded using UTF-8, UTF-16, and UTF-32 representing character sets using 8, 16, and 32 bits respectively. UTF-16 can represent 65,536 characters.)

binary

the binary, or the base-2, positional numbering system represents numerical values using only two symbols, 0 and 1

bit

a contraction of binary digit; the smallest unit of information, having two possible values: 0 and 1. A data element consisting of n bits has 2ⁿ possible

boolean

a data type with two possible value representing true and false.

boolean expression

an expression in a programming language that produces a boolean value when evaluated, i.e., true or false

byte

a number made up of 8 bits. Essentially, all currently manufactured computers use a byte as the smallest unit of storage in memory

cache memory

a special, super-high-speed memory unit. Operating on the principle of locality, which says that when the computer uses something it will probably use it again very soon, when the computer references a piece of data for the first time, it stores that data in cache memory, and when it needs to fetch a piece of information, it first looks in cache memory before performing a memory fetch. Since accessing cache memory is so much faster (typically 5 to 10 times faster) than accessing RAM, it is still faster to access cache memory first and then look in RAM if the data is not found (the cache hit rate tells us just how much faster).

cast

Explicitly converting a value from one type to a different type

class

a programmer defined data type, may be a blueprint or template for creating an object

computer

the study of algorithms, including their formal and mathematical properties, their hardware realizations, their linguistic realizations, and their applications

constructor

A set of statements for initializing a newly instantiated variable

control unit

Unit within the computer that actually carries out the operations of a program. the control unit does three things: fetches from memory the next instruction to be executed, decodes it, and executes it by issuing the appropriate command to the ALU, memory, or I/O controllers. It halts when the last instruction in the program is reached.

encapsulation

The hiding of implementation details

explicit parameter

A parameter of a method other than the object on which the method is invoked

flops

floating-point operations per second

formal parameter

a variable in a method definition; it is initialized with an actual parameter value when the method is called

gigabyte

1 billion bytes. In binary, technically 2^30 bytes, or 1 073 741 824 bytes