AP Computer Science Principles - Vocabulary Set - Unit #4

kilobyte to gigabyte

A KB is 1,024 bytes, not one thousand bytes as might be expected, because computers use binary (base two) math, instead of a decimal (base ten) system. Computer storage and memory is often measured in megabytes (MB) and gigabytes (GB). A medium-sized novel contains about 1 MB of information. 1 MB is 1,024 kilobytes, or 1,048,576 (1024x1024) bytes, not one million bytes. Similarly, one 1 GB is 1,024 MB, or 1,073,741,824 (1024x1024x1024) bytes.

terrabyte to yottabyte

A TB is 1,024 GB; 1 TB is about the same amount of information as all of the books in a large library, or roughly 1,610 CDs worth of data. A petabyte (PB) is 1,024 TB. 1 PB of data, if written on DVDs, would create roughly 223,100 DVDs, i.e., a stack about 878 feet tall, or a stack of CDs a mile high. Indiana University is now building storage systems capable of holding petabytes of data. An exabyte (EB) is 1,024 PB. A zettabyte (ZB) is 1,024 EB. Finally, a yottabyte (YB) is 1,024 ZB.

Student-developed procedure / algorithm

Program code that is student-developed has been written (individually or collaboratively) by the student who submitted the response. Calls to existing program code or libraries can be included but are not considered student-developed. Event handlers are built in abstractions in some languages and will therefore not be considered student-developed. In some block-based programming languages, event handlers begin with "when".

Parameter

An input variable of a procedure, method, or function.

List

An ordered sequence of elements. The use of lists allows multiple related items to be represented using a single variable. Lists are referred to by different terms, such as arrays or arraylists, depending on the programming language.

Output

Any data that are sent from a program to a device. Program output can come in a variety of forms, such as tactile, audible, visual, movement or text.

Input

Data that are sent to a computer for processing by a program. Input can come in a variety of forms, such as tactile (through touch), audible, visual, or text. An event is associated with an action and supplies input data to a program.

Abstraction

Reducing information and detail to focus on essential characteristics. One of the key concepts of object-oriented programming (OOP) languages. Its main goal is to handle complexity by hiding unnecessary details from the user. That enables the user to implement more complex logic on top through the use of a coding language without understanding or even thinking about all the hidden complexity.

Sequencing

The application of each step of an algorithm in the order in which the code statements are given.

Program functionality

The behavior of a program during execution and is often described by how a user interacts with it.

List being used

Using a list means the program is creating new data from existing data or accessing multiple elements in the list.

digital data

information stored on a computer system as a series of 0's and 1's in a binary language. Information is stored on computer disks and drives as a magnetically charged switch which is in either a 0 or 1 state. A single 0 or 1 is also called a bit.

bit

A binary digit, the smallest increment of data on a computer. A bit can hold only one of two values: 0 or 1, corresponding to the electrical values of off or on, respectively. Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of eight to form a byte. A byte contains enough information to store a single ASCII character, like "h".

Program Code Statement

A collection of program statements that are part of a program. For text-based, the collection of program statements should be continuous and within the same procedure. For block-based, the collection of program statements should be contained in the same starter block or what is referred to as a "Hat" block.

Algorithm

A finite set of instructions that accomplish a specific task. Every algorithm can be constructed using combinations of sequencing, selection, and iteration.

Procedure

A named group of programming instructions that may have parameters and return values. Procedures are referred to by different names, such as method or function, depending on the programming language.

top down design

A programming style, the mainstay of traditional procedural languages, in which design begins by specifying complex pieces and then dividing them into successively smaller pieces. The technique for writing a program using top-down methods is to write a main procedure that names all the major functions it will need. Later, the programming team looks at the requirements of each of those functions and the process is repeated.

Iteration

A repetitive portion of an algorithm which repeats or loops until a given condition is met or a specified number of times. The use of recursion is a form of iteration.

Collection type

Aggregate or gathered elements in a single structure. Some examples include: databases, hash tables, dictionaries, sets, or any other type that aggregates elements in a single structure.

Data has been stored in this list

Input into the list can be through an initialization or through some computation on other variables or list elements.

Purpose

The problem being solved or creative interest being pursued through the program.

Argument(s)

The value(s) of the parameter(s) when a procedure is called.

Selection

This determines which parts of an algorithm are executed based on a condition being true or false. The use of try / exception statements is a form of selection statements.

procedural abstraction

This idea, that each conceptual unit of behavior should be wrapped up in a procedure.

Program documentation

This is important to tell other programmers what the program does and how it works. In the "real world" programmers often work in teams to develop code. Documentation helps others on the team to understand your work.