Page 12 - Handout Computer Network.

• The logical connection—The logical connection uses standards called protocols. A
protocol is a formal description of a set of rules and conventions that govern how
devices on a network communicate. Connections to the Internet may use multiple
protocols. The Transmission Control Protocol/Internet Protocol (TCP/ IP) suite is the
primary protocol used on the Internet. TCP/IP is a suite of protocols that work together
to send and receive data.

• Applications—The application that interprets the data and displays the information in
a comprehensible format is the last part of the connection. Applications work with
protocols to send and receive data across the Internet. A web browser displays HTML
as a web page. File Transfer Protocol (FTP) is used to download files and programs
from the Internet. Web browsers also use proprietary plug-in applications to display
special data types such as video, audio, and animation.

This introductory view might make the Internet seem like an overly simple process.
However, as this topic is explored in greater depth later in this book, it will become apparent that
sending data across the Internet is a complicated task.
https://www.youtube.com/watch?v=93-3zmVvCGU&t=22s

1.3 Network Interface Cards

NIC is a printed circuit board that provides network communication capabilities to and
from a PC. Also called a LAN adapter, a NIC plugs into a motherboard and provides a port for
connecting to the network. The NIC constitutes the computer interface with the LAN. The NIC
communicates with the network through a cable and with the computer via an expansion slot.
When a NIC is installed in a computer, it requires an interrupt request (IRQ) for service from the
CPU, as well as an input/output (I/O) address, a memory space for the operating system (such as
Linux or Windows), and drivers to perform its function. An IRQ is a signal that informs a CPU that
an event needing its attention has occurred. An IRQ is sent over a hardware line to the
microprocessor.
An example of an interrupt being issued is a key being pressed on the keyboard. The CPU
must move the character from the keyboard to RAM. An I/O address is a location in memory used
to enter data into or retrieve data from a computer using an auxiliary device.
When selecting a NIC for a network, consider the following:

• Type of network—Different types of networks use different types of NICs. For example,
Ethernet NICs are designed for Ethernet LANs. Some other types of networks include
Token Ring and Fiber Distributed Data Interface (FDDI). Ethernet is by far the most
common.

• Type of medium—The type of port or connector used by the NIC for network
connection is specific to the medium type, such as twisted-pair, coaxial, fiberoptic, or
wireless. Coaxial is becoming increasingly rare.

• Type of system bus—There are different types of system buses, such as PCI and ISA.

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