AP Computer Science - Chapter 1

byte

1 byte = 8 bits. Often used when one must express large numbers to store data.

LAN

A LAN, or local-area network is made for connecting computers that are in close range of each other. Spaces such as office buildings or rooms constitute close ranges. Because the information and computers in a small setting are easy to track, LAN is usually reliable.

URL*

A URL, or Uniform Resource Locator, is found with every web page or document. A URL specifies the information found on the web browser. A URL contains the protocol, the Internet address of wherever the document originated, and the file name.

WAN

A WAN, or wide-area network connects at least two pre-formed LANs and are generally used across long range distances.

bit

A bit is a single numerical value "1" or "0" that denotes a single unit of digital information.

compile-time error*

A compile-time error is simply an error discovered by the compiler, and must be corrected before the program can run much less execute.

compiler

A compiler is simply a program used in translating code to different languages of code. It is often used by the CPU to translate source code.

Internet address*

A distinct feature in every computer made, the Internet address is the equivalent of the computer's name. The name is unique to each computer.

logical error*

A logical error involves no syntax errors, but an element of the code that the programmer meant to be something else. For example, printing rather than prompting results in a valid response, but not the intended one.

Java

A popular programming language because it was the first language created specifically for the Web and is not as picky about details as some other languages, making it easier to work with and learn about programming.

protocol

A protocol is a set of standard rules and procedures about communication between networks.

program

A sequential series of instructions that tells the hardware of a computer what to do in an orderly manner.

browser*

A software tool that formats web pages and documents that are optimal for viewing. A browser adjusts to the screen size of the computer the user is on.

character string

A string is a sequence of characters, denoted by quotes in Java coding. In a println method, the code being "printed" is the string between the double quotes following the main method.

binary number system

A system of numbers that consists entirely of 1s and 0s. Commonly used to store information in an efficient, cheap, and space-conserving manner.

top-level domain*

A top-level domain, or TLD, is the last part of a domain name. This indicates the type of organization that owns the computer, such as "edu" or "org," describing a school and an organization, respectively.

case sensitivity

Because Java is case-sensitive, it's important to pay special attention when coding in order to not confuse identifiers that should be constant throughout the code but are muddled due to one accidentally capitalized letter.

runtime error*

Because the program passed the stage where syntax errors would be caught, a runtime error involves an error in which the program cannot execute. This could potentially cause the program to crash or terminate long before the end.

low-level language*

Both machine and assembly languages are examples of low-level languages which execute basic tasks efficiently.

Von Neumann

Both the idea and the computer system model that utilizes storing of program instructions and data as a package in the main memory.

coordinate system

Representing each point in Java, the coordinate system is simply a pair of (x,y) values.

CPU

CPU = Central Processing Unit. The CPU processes software by converting input commands to executed commands in a program.

method invocation

Calling, or invoking, a method during a program's execution puts the method into action.

syntax error*

Checked by the compiler, syntax must be exact in order for a program to run in Java. A syntax error alerts the programmer that they most likely accidentally repeated or skipped part of the code.

class definition

Class definitions are used to define any Java program. Though they can be called anything, all class definitions run as the code included in the braces following the naming of a class.

primary colors

Consist of red, green, and blue. These colors are "primary" meaning that no other two colors mix to from them, and all other colors are made by mixing them together.

programming process

Consists of multiple steps that, in order, include understanding what the problem is, breaking the problem down into small chunks that are easier to handle, coming up with multiple solutions until the best is found, going through with the solution, and finally testing the solution and troubleshooting if necessary

hardware

Consists of the tangible components of a computer. This includes anything that plugs into the computer or connects as part of the computer system (not just the monitor and keyboard.)

computer architecture

Describes the structure of the hardware components in a computer and their physical relations to each other.

debugging

The process of debugging includes correcting any of the previous errors found by the programmer or the compiler in the program. Once debugging is complete, the program can run the way the programmer intended! (coined by Grace Hopper)

semantics

The semantics of a programming statement determine the result of executing a statement. The better defined the semantics, the easier to understand the statement.

pixel

The smallest element of a picture, a pixel is simply a small piece of a much larger picture. By storing the color of each pixel individually, the computer can effectively reconstruct the picture simply by ordering the square pixels.

program termination

The termination of a program is when every line of code or every programming statement in the main method is completed line by line and has finally reached the end of the method. At this point, the computer stops running the program, or terminates.

user interface

The user interface allows communication between the user and the computer. The simpler the user interface (not necessarily basic) and easier to understand, the more people will be able to use the computer and operating system.

programming statements

These are the input commands that are followed out by the computer when the program is run.

program counter

To help organize pending instructions, the program counter holds the specific address of the next instruction sent to the CPU to be executed.

white space

White space is anything between the characters, words, numbers, symbols, etc. used in a program. This can include spaces, blanks, space between new lines, and so on. The purpose of white spice is to make code easier to read, because a cramped program can't easily be fixed in case it fails to run.

network

With the simple goal of sharing information, a network consists of at least two computers in communication in the hopes of exchanging data. The stronger the network, the easier it is for computers to send large amounts of data to remote locations in less amounts of time.

RGB value

RGB = Red Gleen Blue Value, or number that represent colors in Java.

ROM

ROM = Read-Only Memory, which is another type of memory device. Whenever information is stored on ROM, that information can't be changed, hence the user can "read-only" what is before them.

controller

Act as the middlemen between peripheral devices and the CPU or main memory. The controller must manage the individual aspects of each device's process of sending data.

data transfer device*

Allow the sending of information between computers; almost the exact opposite of physically walking information over to a different computer and then copying it.

interpreter

An interpreter does a similar job as a compiler except for the fact that an interpreter breaks translation/execution into blocks. Rather than translate the entire source code, then execute, the interpreter translates and executes small sections at a time. This eliminates the need for two phases: translation and compilation.

analog technology*

Analog technology is the continuous portrayal or transmission of analog information.

registers

Another part of the CPU, registers are small storage spaces in the CPU.

inline documentation

Any of the examples listed above are part of inline documentation if they are actually in the program.

documentation

Documentation consists of any comments in a program as well as documents such as instructions for the user, references to other sections of code or programs, or any other notes the programmer needs in the program even if they won't actually run in the program.

network address

Every computer in a network has its own network address. This address identifies the computer within a network, and is especially useful when information is being shared in the network.

application*

Excluding the operating system, practically every other software run on a computer can be classified as an application. Applications include anything from games to 3-D modelling, and include individual user interfaces.

arithmetic logic unit

Final part of the CPU, the arithmetic/logic unit is the decision-making center of the CPU, where all the calculations are completed.

GUI

GUI = Graphic User Interface ; Generally used in modern operating systems. A GUI uses graphical components on the screen of a computer (such as arrows, shortcut icons, etc.)

control unit

Handles processing steps of the Central Processing Unit. (CPU)

high-level language*

High-level language is a more modern way that programmer write software as it incorporates hundreds of the basic instructions found in low-level language into a single statement. Java and C++ are examples of high-level languages.

World Wide Web

How we access the Internet. Uses hypertext to access various forms of information on networks of the Internet, and makes sharing of information around the world much more efficient.

I/O Device

I/O device = Input/Output Device. This includes a microphone, keyboard, mouse, speakers, monitor, etc. In short, anything that allows the user to interact with a computer and vice versa.

IDE*

IDE = Integrated Development Environments are user-friendly packages of an editor, compiler, and other Java tools.

IP

IP = Internet Protocol, which lays out the process for formatting and transferring information across networks such as the Internet.

identifiers

Identifiers are, quite simply, words not surrounded by quotes in programming. These identifiers can either (a) be made up by the programmer based off of the program's topic, (b) be commonly used words made by another programmer that denote a certain action within a program or (c) words that only work in specific situations in the Java language.

volatility

If information is volatile, this means that the data stored will be lost if electric power supply to the computer is cut off. This is the reason that it's extremely important to save work before the battery dies.

Internet

Internet, or "internetworking" is, at its base, a WAN. More specifically, the Internet is a vast network of LAN and WAN networks. The Internet connects smaller networks together all as part of a huge WAN network.

architecture neutrality

Java is architecture neutral, which means that its bytecode doesn't have to work with a specific type of processor. Java can work on many different types of machines, although the machines must have a bytecode compiler or translator.

syntax

Just as in any spoken language, every programming language has syntax that determines statements are formed from the vocabulary elements available. Just as a spoken sentence must have a certain structure to be understandable, so does a program statement.

operating system*

Most central software of any computer. The OS is where the user interface is located, which allows communication between the computer and the user. Secondly, the CPU and main memory are managed by operating system in order to help the OS decide when programs can run or share information into the main memory. A comprehensible operating system is crucial in any product that must be marketed and user-friendly.

peripheral*

Most of the devices in a computer system are peripheral, which means that they operate in the outskirts of the computer system and don't allow the user to directly interact with the CPU/main memory. Examples include the keyboard, monitor, disk drives, etc.

OOP

OOP = object-oriented programming; Java is an example of an OOP language that uses basic pieces of information called objects that form a program.

machine language*

One of the four groups of programming languages, the machine language contains any programs that want to run on the computer. An individual instruction in this language can do a basic task, thus the computer can efficiently solve complex problems by breaking instructions into small, easily solvable parts. However, the language uses binary notation and is hard to understand.

editor*

One type of software tool, an editor allows the programmer to easily and efficiently make changes to a program. When translating code into different language that can be executed, errors may occur that must then be fixed in an editor in order for the program to run.

open source

Open source projects and code are released by companies in order to let other programmers work on the code for free in the hopes of improving software as a community and opening up code to suggestions from millions of people.

fourth-generation language*

Operating at higher levels even than the high-level languages, fourth-generation language ignores the details of machine language and instead is used for interactions with a database or longer computer-automated tasks.

software*

Programs and the information, or data, contained in these programs make up software on a computer.

RAM

RAM = Random Access Memory, from which data can be read and to which data can be written. RAM is a type of memory device.

reserved words

Reserved words are a class of identifiers that can only be used in specific ways in a program because of their special function.

SDK

SDK = Software Development Kit = JDK contains tools that can aid the programmer. This kit consists of commands that the programmer can use in the command window.

bytecode

Similar to machine language code, Java bytecode is translated by the Java compiler to easily work on various machines.

source code

Source code is the original code in terms of translation. Before the translation, the source code remains, and after the code is now in the target language.

second memory

Stores software for the computer's lifespan or forever unless erased by the user by hand. Secondary memory devices can include removable hardware such as floppy disks and CDs which are portable.

subdomain*

Subdomains are often assigned to individual schools (rather than on a large-scale level) that are further additions to the basic domain name.

main memory

Temporary memory that only holds software when the programs are being processed by the CPU. Main memory does not usually entail long-term storage of software.

ARPANET

The Advanced Research Projects Agency developed a WAN called Arpanet that became what we know as the Internet.

domain name*

The domain name of an Internet address tells the user about the organization that owns the computer. Domain names are also unique, which prevents confusion.

instruction register

The instruction register of the CPU holds the current instruction in its state of execution while it's being executed.

microprocessor

The microprocessor is the chip upon which the CPU operates. It's part of the hardware of the computer in the main circuit board.

title case

Used in Java (also called Camel case) for class names. The constant format used lessens mistakes when retyping identifiers. When using title case, the first letter of each word of the identifier is capitalized.

assembly language*

Uses mnemonics rather than binary, employing words similar to English that can give instructions or send data. Although it is easier to read and write for humans, all instructions must be translated into the machine language before they can be carried through in the computer. (not as efficient)

digital technology*

Using digital technology, the computer instead translates chunks of information into numbers

file server

Usually built with a large amount of secondary memory, the file server serves its purpose of storing programs/data in a network. Any computer in the network can draw data from the file server when necessary. This way, each computer in the system doesn't have to download a copy of a program.

digitized data

When data undergoes the process of being divided into separate pieces and being translated into numbers, the data is said to have been digitized.