Computer Architecture Overview

Computer Architecture

• The CPU (Central Processing Unit) contains the control unit and arithmetic/logic unit.
• The control unit coordinates data and instruction transfer between main memory and CPU registers.
• The arithmetic/logic unit performs operations on data in registers.
• The instruction register holds the current instruction being executed.
• The program counter stores the address of the next instruction to be executed.
• General-purpose registers are used for temporary data storage.
• The von Neumann architecture combines program instructions and data in main memory.
• The fetch-decode-execute cycle is the foundation of computer processing.
• The CPU is implemented on a microprocessor chip, which is part of the main circuit board.
• The main circuit board contains ROM chips, communication sockets, and a system clock.
• The system clock generates electronic pulses to synchronize CPU events.
• The rate of pulses is the clock speed.
• A simple computer network can include multiple computers connected to a printer and a file server.
• A file server stores programs and data for many network users.
• A network can use point-to-point connections for direct communication between computers.
• Point-to-point connections require a separate wire for each connection.
• Local networks often use wireless connections.
• Computers on a network share a single communication line with unique network addresses.
• A message is sent to another computer by specifying its network address.
• Domain names are used to identify computers on the Internet, such as vt.edu for Virginia Tech.
• Subdomains distinguish computers within a larger organization, like cs.vt.edu for Virginia Tech's Computer Science department.
• Top-level domains (TLDs) indicate an organization's type, such as edu for education, com for commercial, and org for nonprofit.
• Country-code TLDs indicate the country of origin, like .uk for the United Kingdom.
• The Domain Name System (DNS) translates domain names to IP addresses.
• Domain servers maintain lists of computers and their IP addresses.
• The Internet allows information exchange, facilitating communication between computers.
• The World Wide Web (WWW) makes information exchange accessible to humans.
• Web software provides a common user interface for accessing information.
• The Web is based on hypertext and hypermedia concepts.

Java Programming Concepts

• Identifiers are the words used in program code.
• Some identifiers are user-defined, such as class names and variable names.
• Others are predefined by other programmers, like class names from the Java standard library.
• Reserved words have special meaning in Java and cannot be used for other purposes.
• Java reserved words are highlighted in blue throughout the book.
• Valid identifiers can be any combination of letters, digits, underscores, and dollar signs, but must start with a letter or underscore.
• Identifiers can be any length.