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

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

Functions of an Assembler

The fundamental task of an assembler is to translate a program in assembly language to code for machine language. In essence, the assembler must perform the following tasks:

• Convert the code (opcode or mnemonic: e.g., LDA, STX) to the equivalent code in machine language.
• Convert symbolic operands (tags or variables) into the addresses of the operands.
• Build the machine language instructions in the appropriate format.
• Convert the constants defined in the program into their true representation.
• Write the "listing" in assembly language to machine language code.
• Process the assembly guidelines. The guidelines are instructions or commands directed to the assembler, which it processes and executes as it encounters them in the assembly

DHCP: Dynamic Host Configuration Protocol

DHCP (Dynamic Host Configuration Protocol) is a service created by the IETF in 1993 that operates at the network level. It provides a rapid mechanism for network configuration. UDP is the protocol used by clients to automatically obtain IP addresses.

Configuration Options

• IP Address
• Subnet Mask
• Default Gateway
• DNS Server
• Domain Name
• DNS Suffix Name
• Node Type (Windows)
• Renewal Time
• Reconnection Time

WINS (Windows Internet Name Service) is a Microsoft service that resolves NetBIOS names to IP addresses. MAC addresses are a sequence of 6 groups of hexadecimal digits that uniquely identify a network interface. The first 3 digits control the manufacturer.

Lease: When an IP address is assigned to a client, the lease indicates... Continue reading "Understanding DHCP: Configuration, Protocols, and Advantages" »

Understanding System Interrupts and Functions

System interrupts are crucial for managing CPU operations and external device interactions. They can be broadly categorized into:

• CPU Interrupts: These are internal events, often referred to as software interrupts or exceptions, triggered by the CPU itself.
• Hardware Interrupts: Caused by external devices, signaling the CPU for attention (e.g., keyboard input, disk I/O).

Essential System Services and Functions

Beyond interrupts, various basic services are available for program interaction with the system:

ROM BIOS Functions

Functions available directly in the system's Read-Only Memory (ROM).

DOS BIOS Services

Basic functions provided by the Disk Operating System (DOS).

DOS Functions

High-level functions for... Continue reading "Assembly Language Fundamentals: Interrupts, Memory, and MASM Directives" »

Software Classification

We can classify software into three types:

• Operating Systems: Manage computer resources.
• Programming Languages: Used to build applications (e.g., Java, C++, Assembly).
• Applications and Programs: Perform specific operations.

Programming Languages

What are Programming Languages?

Programming languages are established systems of communication understood by both programmers and machines, used to develop programs. They are constantly evolving, with many based on English, but increasingly visual and intuitive.

Word Processors

What is a Word Processor?

Word processors offer more than just writing; they allow for the inclusion of photos and drawings, text justification and formatting, spell checking, and integration with other applications.... Continue reading "Software Types, Computer Uses, and IT in Special Education" »

Operating Systems

What are operating systems? This question can be answered at several levels.

Firstly, an operating system is a program, or a set of programs. Operating systems vary in size from very small to very large, but all are pieces of software. In the past, almost all operating systems were written in a low-level language. Currently, many operating systems are partly or completely written in a high-level language.

Secondly, an operating system is, by virtue of its name, a system. It is a collection of parts working together towards some common goals. The goals or objectives of an operating system may be regarded as the manager of these resources.

Thirdly, a computer may be regarded as a set of devices, or resources, which provide a number... Continue reading "Understanding Operating Systems: Definition and Functions" »

TCP/IP Protocol Suite Characteristics

• Based on open and free protocols and standards.
• Provides software and hardware independence.
• Uses a common addressing scheme allowing any TCP/IP device to locate another anywhere on the network.
• Includes high-level, standardized protocols supporting widely available and consistent user services.
• Acts as a de facto standard for networking.
• Allows the interconnection of networks with diverse features and technologies.

Internet Protocol Family Fundamentals

The Internet protocol family, commonly known as TCP/IP, is a set of network protocols fundamental to the Internet, enabling data transmission between computer networks. Examples include HTTP, ARP, Telnet, and POP.

Understanding Routers and Their Function

Routers are... Continue reading "Core Networking Concepts: TCP/IP, Routers, and DNS" »

Understanding Wide Area Networks (WANs)

A WAN (Wide Area Network) spans a large geographic area, sometimes a country or continent. It contains a collection of machines dedicated to running user programs. These machines are called Hosts. The hosts are connected by a communication subnet. The subnet's job is to conduct messages from one host to another. The separation of the unique aspects of the communication network (subnet) and areas of application (hosts) greatly simplifies the overall design of the network.

Key Components of a WAN

• Switching Computers (ECD): Each ECD uses a protocol responsible for routing the data correctly and providing support to computers and end-user terminals connected to it.
• Computer User (DTE): The DTE support function

Disney Transport Layer Considerations

The transport layer is the heart of the whole hierarchy of protocols.

Function: To provide efficient, reliable, and economic data transport processes for the application layer, regardless of the physical network or networks.

There are two types of service: connection-oriented and connectionless.

If there is an error in the lower layers, where n can be controlled at higher x, the error is corrected at the transport layer.

• Disorders
• Duplication
• Loss

Causes of errors:

• Cable errors
• Interference
• Inadequate blockade operation

Functions in the Transport Layer

• End-to-end reliable communication
• Error control
• Flow control
• Multiplexing of several connections

Origin and destination communicate through a network. The transport layer... Continue reading "Disney Transport Layer: Understanding Network Communication" »

Biometric Systems: Enhancing Security

Biometric systems, applied to information systems, allow for the authentication of individuals using electronic technologies. These technologies employ complex mathematical formulas to ensure that the person applying for entry to a resource, or a physical space, is who they claim to be.

Increased Security with Biometric Access Systems

Personal identification methods to control access are based on:

• Something you know: passwords or access keywords.
• Something you own: for example, an encoded magnetic card.
• A personal characteristic: such as fingerprints or iris.

Combining two or more methods provides an even higher level of security.

Biometrics: Key Characteristics

• Universality: All individuals possess this characteristic.