Java An Introduction to Problem Solving and Programming Chapter 1.1 (Notes)

Hardware and Software

Hardware and Software make up a computer system

Hardware and Memory

• The CPU, or central processing unit, or processor, performs the instruction in a program.
• Main memory is volatile: auxiliary memory is not.
• Main memory consists of addressable eight-bit bytes.
• Group of adjacent bytes can serve as a single memory location.
• A file is a group of bytes stored in a auxiliary memory.
• A directory or folder, contains a group of files.
• Each byte can hold eight binary digits, or bits, each of which is either 0 or 1.

Programs

• A program is a set of computer instructions
• An operating system is a program that supervises a computer's operation.

Programming Languages, Compilers, and Interpreters

• Java is a high-level language.
• Computers execute a low-level language called machine language.
• Compile once, execute often.
• Compilers translate source code into object code.
• Interpreters translate and execute portions of code at a time.

Java Bytecode

• A computer translate Java code into bytecode.
• The JVM is an interpreter that translate and executes bytecode.
• Java bytecode runs on any computer that has a JVM.