CS1140 Chapter 1: Introduction to Computers, Programs, and Java

Computer

An electronic device that stores and processes data.

Hardware

The physical aspects of a computer that can be touched.

Software

The invisible instructions (programs) that control hardware to perform tasks.

Computer programming

The writing of instructions (code) for computers to perform.

Central Processing Unit (CPU)

The computer's brain that retrieves instructions from memory and executes them.

Bit

A binary digit representing a 0 or a 1.

Byte

A sequence of 8 bits.

Kilobyte (KB)

A unit of memory equal to about 1,000 bytes.

Megabyte (MB)

A unit of memory equal to about 1 million bytes.

Gigabyte (GB)

A unit of memory equal to about 1 billion bytes.

Terabyte (TB)

A unit of memory equal to about 1,000 gigabytes.

Memory (RAM)

Stores data and program instructions for the CPU to execute.

Memory unit structure

An ordered sequence of bytes.

Volatile memory

Memory whose stored information is lost when power is turned off.

Storage devices

Devices that permanently store programs and data.

Machine language

A set of primitive computer instructions built into every computer.

Assembly language

A low-level language using mnemonics to represent machine-language instructions.

High-level language

An English-like programming language that is easy to learn and use.

Source program (Source code)

A program written in a high-level programming language.

Compiler

Software that translates source code into machine language or bytecode.

Operating System (OS)

Program that manages and controls a computer's activities.

Platform independence

Ability to write a Java program once and run it on any computer.

Java source file extension

The .java extension, matching the public class name.

Java bytecode file extension

The .class extension generated after compiling a Java class.

javac command

Command-line tool used to compile a Java source code file.

java command

Command-line tool used to execute a compiled Java class.

Class keyword

The keyword used to introduce a class definition in Java.

Java block

A group of Java statements enclosed in braces: { and }.

Java main method

The entry point where a Java program begins execution.

Statement terminator in Java

The semicolon (;) used to mark the end of a statement.

Keywords (Reserved words)

Words with specific compiler meanings that cannot be used for other purposes.

Line comment in Java

A comment preceded by two slashes (//) on a single line.

Block comment in Java

A multi-line comment enclosed between /* and */.

Java case sensitivity

Java distinguishes between uppercase and lowercase letters in source code.

Three types of programming errors

Syntax errors, runtime errors, and logic errors.

Syntax error (Compile error)

An error detected by the compiler due to incorrect code structure.

Runtime error

An error that causes a program to terminate abnormally during execution.

Logic error

An error occurring when code runs but produces incorrect results.

Application Program Interface (API)

A set of predefined classes and interfaces for building Java software.

Assembler

A program that translates assembly language code into machine code.

Bus

A system of channels connecting computer components to transfer data.

Bytecode

Low-level, architecture-neutral code compiled from Java source files.

Bytecode verifier

Component ensuring Java bytecode is valid and safe to execute.

Class loader

JVM component that loads required class files into memory.

Integrated Development Environment (IDE)

Software providing comprehensive tools for editing, compiling, and debugging code.

Interpreter

Software that reads and executes high-level code or bytecode line by line.

Java Development Kit (JDK)

Software bundle containing tools to develop and compile Java programs.

Java Runtime Environment (JRE)

Software bundle providing the libraries and JVM required to run Java programs.

Java Virtual Machine (JVM)

An abstract computer that interprets and executes compiled Java bytecode.

Network Interface Card (NIC)

Hardware device connecting a computer to a local area network.