Notes, summaries, assignments, exams, and problems for Computers

Digital Sound Features

Sample Rate: The number of samples per second taken from a continuous analog signal to make a discrete digital signal. For example, CD-quality digital audio uses 44,100 Hz.

Channels: The number of audio channels in a sound recording. Mono = 1, Stereo = 2, 5.1 = 5 channels.

Sample Size: Indicates the number of bits of information in each sample. CD-quality audio uses 16 bits.

Formula: Size = Frequency x Sample Size x Number of Channels x Time (in seconds).

Audio Formats

WAV: A digital audio format without compression. It supports mono and stereo files, and its extension is .wav. It is seldom used on the internet. Microsoft and all programs recognize it.

MIDI: A protocol for communication between digital musical instruments and... Continue reading "Digital Sound and Video: Formats, Properties, and Tools" »

System Modeling Fundamentals

A model is an abstract representation of a real object. The first model developed is crucial as it defines the interfaces between the system and its environment. This initial model is known as the environmental model, describing the immediate context in which the system operates according to its objectives.

Components of the Environmental Model

1. Statement of Purpose (Objectives)

   This is a short and concise textual statement defining the system's purpose.

2. Context Diagram

   The Context Diagram graphically shows how the system interacts with the environment, making it easy for a user to interpret.

   It is a special case of a Data Flow Diagram (DFD), where a single bubble represents the entire system.

   Important Features Represented:

Data

Data is the collection of facts considered in isolation. It describes an organization and carries meaning, but generally is not useful by itself.

Information

Information is data that has been manipulated and is useful to someone. Information must have value; otherwise, it would be considered just data. Information tells people something that confirms what they knew or suspected. (What, who, and when?)

Why? Because telecommunication networks transmit data, the networks do not identify meanings (information). The objective of networking is to take data from one place to another.

Data Types

• Analog: Continuous
• Digital: Discrete

Symbols limited by their use and origin:

• Alphanumeric
• Graphic
• Image
• Audio
• Video
• Multimedia

Model of a Basic Communication System

Components:... Continue reading "Data, Information, and Network Communication Essentials" »

Key Networking Concepts and Components

Definitions of Wireless and Wired Technologies

• Wi-Fi: Short for Wireless Fidelity, this term names the set of protocols for wireless networking through radio frequency.
• Bluetooth: A wireless communication protocol that uses radio frequencies and allows a range of up to 10 meters.
• Switch: A device used in cable network connections that toggles or selects the position to prioritize information at any time, ensuring data packets reach only their intended recipient.
• Hub: A device that allows the connection of multiple computers using a wired network. Data received are sent to all computers connected to it.
• PCI Bus: A bus or connector device located on the motherboard. Sound cards, network cards, capture cards, TV

Networking Essentials: TCP/IP Concepts

TCP Flow Control Purpose

Why is flow control used for TCP data transfer?

• To synchronize the speed of data sent.
• To synchronize and order sequence numbers so data is sent in complete numerical order.
• To prevent the receiver from being overwhelmed by data.
• To synchronize window size on the server.
• To simplify data transfer to multiple hosts.

Analyzing Network Output: Key Information

Refer to the exhibit. What two pieces of information can be determined from the output shown? (Choose two.)

• The local host is using well-known port numbers to identify the source ports.
• A request for termination has been sent to 192.135.250.10.
• Communication with 64.100.173.42 is using secure HTTP.
• The local computer is accepting HTTP requests.

Asynchronous Transfer Mode (ATM) Networks

Integrating Multimedia Services with ATM VPN

The integration of voice and image services within Asynchronous Transfer Mode (ATM) creates a Multimedia Virtual Private Network (VPN). This innovative approach allows services previously provided on separate networks to be consolidated into a single, unified network.

ATM VPNs are based on the concept of a Virtual Private Network, offering resources dedicated exclusively to the client. This is achieved through a shared network infrastructure and a single access point to the network. Integration is facilitated by deploying an integration device at the customer's premises.

ATM Integration Device Capabilities

The integration device can consolidate data, voice, and... Continue reading "ATM and FDDI Networks: Advanced Data Transmission Solutions" »

Software Fundamentals

Software: Part of computer logic. All programs managed by the computer. A set of rules and instructions.

1. System Software (SW Base)

A set of programs that control the computer and form the base of application software. It allows the inner workings and facilitates user interaction and machine-to-machine communication.

1.1 Operating Systems (OS)

The closest layer to the machine, it acts as an intermediary between the user and the machine. It is the first program loaded into memory and is essential to operate the machine. Two types of interfaces exist: text and graphics.

Functions of an Operating System:

• Planning, supervision, and load initialization when running a program.
• Manage all system resources.
• Initiate and control I/O units

Understanding Core Network Protocols and Services

Introduction to Network Fundamentals

• The Internet Control Message Protocol (ICMP) is an IP protocol used for sending control, reporting, and discovery messages.
• Network architectures are built upon dependent levels or layers.
• The complexity of a network directly impacts its reliability.
• Virtual communication is a fundamental aspect of modern media.
• End-to-end flow control is a critical network function.

Transport Layer Protocols: TCP and UDP

• An advantage of including the transport level is that protocols can be designed to conceal underlying network complexities from applications.
• The primary data unit at the transport layer is the Transport Protocol Data Unit (TPDU).
• Transport level protocols include

Application Architecture Network

Telematics applications are the core of this field. The design of protocols and computer networks revolves around supporting these applications. Unlike telecommunications networks designed for voice communication, telematics networks prioritize data and information exchange over long distances.

These applications are primarily software-based. As mentioned previously, internet applications are distributed across end systems or hosts, forming a distributed system.

The distribution method determines the architecture and characteristics of applications within computer networks and distributed systems. One example is the client/server architecture.

Client/Server Architecture

In this model, a host acts as a server, running... Continue reading "Telematics and Application Protocols" »

Chapter 1: Local Area Network (LAN) Fundamentals

A local area network (LAN) includes the components, both software and hardware, that enable microcomputers, PCs, and peripherals within a limited geographical area to communicate with each other. LANs also facilitate the distribution and sharing of all system resources between different units.

Key Characteristics of a Local Area Network

• Limited geographical area
• High transmission speed (from 1 Mbit/s to 1 Gbit/s)
• Low error rate
• Entire network is owned and managed by the user

These LANs can be interconnected in various ways using repeaters, bridges, gateways, routers, or switches.

Local Area Network Objectives

• Allow secure communication at a reasonable cost
• Be structured in levels, allowing changes by level