IB Computer Science HL Vocab Flashcards

Terms Definitions
Abstract Data Structure
A way of organizing data and its related procedures and functions.
Accessor methods
Methaods that do not alter the state or attributes of an object; their purpose is to return information.
Accumulator
A storage register in all ALU that holds data temporarily while the data is processed and before it is transerred to memory.
ADSL (Asymmetrical Digital Subscriber Line)
Technology that increases the data rate over existingtelephone lines accommodating voice and digital data transfer. A special modem is needed for access.
argument
A value or object passed to a method when it is called.
Attribute
Element of data contained in an object; as specified within the object’s class.
Balanced tree
A tree in which the right and left subtrees of any node have heights differing by one at the most. See also the definition for “unbalanced tree”.
Behaviour
The way in which an object reacts to the methods applied.
BigO notation
A notation used to describe the relative performance (speed) of an algorithm.
Binary operator
An operator that combines two operands to give a single result, for example, addition, multiplication, division, mod, div. See also the definition for “unary operator”.
Binary tree
A tree in which each node has at most two children.
Circular queue
A queue in which the storage area is fixed and the first item is held in a location that is logically next to the storage location for the last item of the queue. Data items can be thought of as being arranged in a circle.
Clash (collision)
A situation in which two or more entries in a file or other data structure are given the same memory location through the use of a hash table.
command language
A set of procedural operators with a related syntax, used to indicate the functions to be performed by an operating system.
Cylinder
Concentric disk tracks of a hard disk (one on top of the other) form a cylinder.
De Morgan’s law
Dequeue
To remove an item from the front of a queue. See also the definition for “enqueue”.
DMA
Access to memory and devices without the direct control of the processor. This is most often used for hard disk access and screen display.
Double buffering
Two areas of memory set aside for data transfer between the processor and peripherals. As one is emptied the other is filled up in order to speed up transfer.
Doubly linked list
A linked list in which each node has both a head pointer and a tail pointer.
Dynamic data structure
Data structures that can change in size during program execution. See also the definition for “static data structures”.
Encapsulation
The combination of data and the operations that act on the data to form a single program unit called an “object”.
Enqueue
To add an item to the rear of a queue. See also the definition for “dequeue”.
FIFO
First-in-first-out. See also the definitions for “queue”, “stack” and “LIFO”.
Fixed-length records
Records whose size is determined in advance. All such records in a file have the same length. See also the definition for “variable-length records”.
Fixed point
The performing of arithmetical calculations without regard to the position of the radix point. The relative position of the point has to be controlled during calculations.
Floating point
In floating point arithmetic, the position of the decimal point does not depend on the relative position of the digits in the numbers (as in fixed point arithmetic), since the two parts of the floating point number determine the absolute value of the number.
Fully-indexed file
A file in which, although the records are unordered, a particular record can be found using a sequential access to the index of the file followed by direct access to the data file. See also the definition for “partially-indexed file”.
Gateway
A link between two computer systems that converts data passing through into the formats needed for each system.
Handshaking
The exchange of predetermined signals when a connection is established between two devices or components.
Hash code
A method of coding to obtain a search key for the purpose of storing and retrieving items of data.
Hash table
A table of information that is accessed by way of a shortened search key (the hash value).
Infix notation
A notation for representing logical operators in which the operator is written between the operands, for example, A+B or A*B. See also the definitions for “postfix notation” and “prefix notation”.
Inheritance
The name given to the property whereby an object, which extends another object, inherits the data members and member functions of the original.
In-order traversal
Traversal of a tree visiting the nodes in the order left-child, parent, right-child. See also the definitions for “pre-order traversal” and “post-order traversal”.
Insertion sort
A sort in which each item in a set is inserted into its proper position in the sorted set according to a specified criterion. See also the definitions for “bubble sort”, “selection sort” and“quicksort”.
Interrupt
 A suspension of a process, such as the execution of a computer program caused by an external event, performed in such a way that the process can be resumed.
ISDN (integrated services digital network)
An international communications standard for sending voice, video and other data over digital telephone lines.
Keys
1. In computer security, a sequence of symbols used with a cryptographic algorithm for encrypting or decrypting data. 2. In databases, the key of a record is a field with a unique value that can be used to locate that record.
Left-child
In a tree, the node to the immediate left of a parent node. See also the definitions for “parent” and “right-child”.
Library manager
Many programming languages permit user-defined functions to be stored centrally and re-used in various programs. This central storage is called a “library”. A library manager is a utility program that catalogues, pre-compiles and links library modules.
LIFO
Last-in-first-out. See also the definitions of  “stack”, “queue” and “FIFO”.
Linked list
A data structure technique of storing data in different areas of memory rather than in a contiguous block and keeping track of the data using pointers.
Linker
A utility program that brings together the object modules, operating system routines and other utility software to produce a complete, executable program.
Loader
A program that copies an object program held in memory into the memory area designated by the operatingsystem for execution.
Logic circuit
A circuit whose output can be determined by knowing the input and by following the path through the logic gates.
Logic gate
A combinational circuit that performs an elementary logic operation and usually involves one output.
Memory manager
A program that is usually part of the operating system that controls the allocation of memory to various applications. It is particularly important in multi-tasking systems where applications might otherwise cause conflicts, and for implementing virtual machines and virtual memory.
Nand
The output of “nand” is False only if all inputs are True, otherwise the output is True.
Nor
The output of “nor” is True if all statements are False, False if at least one statement is True.
Open systems interconnection (OSI)
A set of protocols allowing different types of computers to be linked together.
Operand
In an arithmetical expression, the operand is the data that is to be operated on.
Operator
A character or string of characters that designate an operation. See also the definitions for “binary operator” and “unary operator”.
Overflow
The generation of a quantity, as a result of an arithmetic operation, that is too large to be contained in the result location. See also the definition for “underflow”.
Packet
A group of bits made up of control signals, error control bits, coded information and the destination for the data.
Packet switching
A method of transmitting data in which the data packet is transmitted as one entity irrespective of the whole message.
Parallel interface
An interface through which a computer transmits or receives data that consists of several bits sent simultaneously on separate wires. See also the definition for “serial interface”.
Parameter
A parameter is passed to a routine or method by variable name and type. When the code is run, the parameter is replaced by the value of the variable, and becomes the argument of the routine, referred to by the variable name in the definition.
Parent (node)
The node immediately above a given node, at the next level up. There can only be one parent node for each node, but different nodes may share the same parent.
Parsing
The breaking down of high-level programming language statements into their component parts during the translation process. An example would be identifying reserved words and variables.
Partially-indexed file
A file in which records are ordered in groups. Sequential access to an index followed by direct access to the first record in the group, then sequential access to the desired record, retrieves a particular record. See also the definition for “fully-indexed file”.
Pointer
A reference to an address that enables the retrieval of a data item or record. Used in dynamic data structures to move from item to item.
Polling
Interrogation of devices for such purposes as avoiding contention, determining operational status, or determining readiness to send or receive data.
Polymorphism
The ability of different objects to respond appropriately to the same operation.
Pop
To remove an item from the top of a stack.
Port
An access point for data entry or exit.
Postfix notation
A method of forming mathematical expressions in which each operator is preceded by its operands and indicates the operation to be performed on the operands or the intermediate results that precede it; for example, A added to B and the sum multiplied by C is represented by the expression AB+C*. See also the definitions for “infix notation” and “prefix notation”.
Post-order traversal
Traversal of a tree by visiting the nodes recursively in the order left- child, right-child, parent. See also the definitions for “pre-order traversal” and “in-order traversal”.
Prefix notation
A method of forming mathematical expressions in which each operator precedes its operands and indicates the operation to be performed on the operands or the intermediate results that follow it. See also the definitions for “infix notation” and “postfix notation”.
Pre-order traversal
Traversal of a tree by visiting the nodes recursively in the order parent, left-child, right-child. See also the definitions for “in-order traversal” and “post-order traversal”.
Program counter
A register that holds the address of the next instruction to be fetched in the fetch execute cycle.
Push
To add an item to the top of a stack.
Queue
An abstract data structure where items are inserted at one end and retrieved from the other end (FIFO). (The standard operations are given in 5.2.7.)
Quicksort
A sort in which a list is first partitioned into lower and upper sublists for which all keys are, respectively, less than some pivot key or greater than the pivot key. See also the definitions for “bubble sort”, “selection sort” and “insertion sort”.
Recursion
The process whereby a method refers to itself. In many programming languages, a procedure or function can call itself.
Reference
Contains the location in memory of an object. The object can contain many individual data members.
Register
A part of internal storage that has a specified storage capacity and is usually intended for a specific purpose.
Right-child
In a tree, the node to the immediate right of a parent node. See also the definitions for “parent” and “left-child”.
Rotational delay
n a disk drive, the time required for the disk to revolve until the correct sector is under/over the read/write heads. See also the definition for “seek time”.
Sector
The smallest accessible storage unit on a disk. The point at which the sector intersects with a track is used to reference the location.
Seek time
In a disk drive, the time taken for the read/write heads to position themselves over the appropriate track. See also the definition for “rotational delay”.
Sentinel
A special value that marks the end of a set of data. Also called an “end of data marker” or “rogue value”.
Serial interface
An interface through which a computer transmits or receives data, one bit at a time. See also the definition for “parallel interface”.
Software reuse
Creating classes that operate on a wide variety of different objects, and can be “dropped into” a current project, leading to reduced software cost and increased reliability.
Stack
An abstract data structure where only the top is accessible for the insertion and retrieval of items (LIFO).
Subclass
A class that extends the attributes and methods of a parent class.
Subtree
A tree that is part of another tree.
Superclass
A class that provides its attributes and methods to a subclass.
Track
A series of concentric rings placed on a disk surface by the operating system.
Tree
A non-linear data structure (representing a strictly hierarchical system of data) where each data item is thought of as a node.
Truncation
1. The process of approximating a number by ignoring all information beyond a set number of significant figures. Truncation error is the error introduced by this process. 2. The deletion or omission of a leading or a trailing portion of a string in accordance with specified criteria.
Truth table
A table that describes a logic function by listing all possible combinations of input values and indicating the output value for each combination.
Two’s complement
A method of representing negative numbers in the binary system.
Unary operator
An operator requiring only one operand to give a single result; for example, negation (overbar for a Boolean expression). See also the definition for “binary operator”.
Unbalanced tree
A tree in which the right and left subtrees have heights differing by more than one. See also the definition for “balanced tree”.
Underflow
The generation of a result whose value is too small for the range of the number representation being used. See also the definition for “overflow”.
Variable-length records
Records whose length is not determined in advance. Each record is allocated the space that it needs to store the information it holds. See also the definition for “fixed-length record”.
Xor
(Exclusive or gate.) The output is True if the two inputs are different; the output is False if the two inputs are alike.
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