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

Introducing Networks

A network is created when more than one device is connected together. A network can be a small collection of computers connected within a building (e.g. a school, business, or home) or it can be a wide collection of computers connected around the world.

Advantages

• Communication – it is easy (and often free) to communicate using email, text messages, voice calls, and video calls.
• Roaming – if information is stored on a network, it means users are not fixed to one place. They can use computers anywhere in the world to access their information.
• Sharing information – it is easy to share files and information over a network. Music and video files, for instance, can be stored on one device and shared across many computers, so

Application Software

System Software

Operating System

Why OS?

Operating System Function

OS Goals

Types of Operating Systems

• Single Process Operating System
• Batch-Processing Operating System
• Multiprogramming Operating System
• Multitasking Operating System
• Multi-Processing Operating System
• Distributed System
• Real Time OS

Program

Process

Thread

Multi-tasking vs Multi-Threading

Thread Scheduling

Thread Context Switching vs Process Context Switching

User Space

Kernel

Functions of Kernel

• Process Management
• Memory Management
• File Management
• I/O Management

Type Of Kernel

• Monolithic
• Micro
• Hybrid
• Nano

System Calls

Types

• Process Management
• Device Management
• File Management
• Information Management
• Communication Management

Firmware: SW embedded in HW (microprocessor -> microcontroller)

What

Internet Technologies

The internet relies on several key technologies:

• Transmission Control Protocol (TCP): Enables connections and data exchange between hosts.
• Internet Protocol (IP): A unique 32-bit numeric address for each computer, represented by four numbers (0-255) separated by periods.
• Domain Name System (DNS): Converts domain names (e.g., google.com) to IP addresses.
• Hypertext Transfer Protocol (HTTP): The standard for transferring web pages.
• Hypertext Markup Language (HTML): Formats documents and links to other resources.
• Uniform Resource Locator (URL): References a web resource's location and retrieval method.

Cloud Computing

Cloud computing provides access to shared computing resources over a network. Different service models exist:

• Software

Computer Hardware

Core Components

CPU (Central Processing Unit)

The CPU controls and executes operations within the computer to process information. It consists of:

• CU (Control Unit): Coordinates all computer activities and manages temporary data storage.
• ALU (Arithmetic and Logic Unit): Performs basic data operations.

Memory

• Random Access Memory (RAM): Enables reading and writing operations, allowing access to random memory locations.
• Read Only Memory (ROM): Contains permanent instructions for computer startup, forming the BIOS (Basic Input Output System).

Input/Output Units

These units facilitate communication between the CPU, internal components, and external devices.

Buses

Buses enable efficient information exchange between computer components. Types... Continue reading "Understanding Computer Hardware and Software Essentials" »

Semantics in Programming

Semantics indicate the meaning of the code, specifically:

• What the code will actually do
• Can we effectively define this in a formal way?

In essence, semantics refers to the meaning of a statement.

Characteristics of Effective Programming Languages

1. Clarity, Simplicity, and Unity

   A programming language should be clear and simple, enabling users to understand it easily. Unity contributes to understandability.

2. Orthogonality

   This term refers to the ability to combine various features of a language in all possible combinations, with each combination being meaningful. For example, if a language provides an expression that can produce a value and a conditional statement that evaluates an expression to yield a true or false result, these

Fundamental Concepts in Knowledge and Data

• The most fundamental combiner is the unification of the Self with itself, which gives rise to the knower, the process of knowing, and the known.
• Normalization is a mathematically interesting, bottom-up technique for producing a set of relations with desirable properties from a set of mathematical dependencies in the data.
• A graphical technique employed by Vedic science is the unified field chart, which provides a holistic overview of a discipline and links all knowledge with the Self.

Data Compression Techniques

Variable-Length Integer Coding (VarInt)

A simple approach to compression is to use only as many bytes as necessary to represent an integer. This technique is known as variable-length integer coding... Continue reading "Core Concepts in Data Processing and Information Retrieval" »

Define SDLC models? What are the most known SDLC model?

An SDLC model defines implementation of an approach to the project. It defines the various processes, and phases that would be carried out throughout the project to produce the desired output. There are a variety of SDLC models that exist catering to different needs and characteristics of a project. Some are of iterative nature (Prototyping), whereas some are sequential (waterfall).

Some of the well-known SDLC models are:
Waterfall model, Software prototyping, Rapid application development,

Extreme programming, and End user development. 

List Advantages of using system analysis and design techniques in approaching computerized info system?

• Identifies and solves the right problems
• Implement

Binary Search Tree (BST)

Binary search tree (BST) is a tree in which all nodes follow the below mentioned properties:

1. The left sub-tree of a node has a key less than or equal to its parent node's key.
2. The right sub-tree of a node has a key greater than or equal to its parent node's key.
3. Binary search tree (BST) divides all its sub-trees into two segments: left sub-tree and right sub-tree and can be defined as left_subtree (keys) ≤ node (key) ≤ right_subtree (keys).

Red-Black Tree

A red-black tree is a binary search tree in which each node is colored red or black. The root is black. The children of a red node are black. Every path from the root to leaf has the same number of black nodes and all leaves are black.

AVL Tree

Adelson, Velski & Landis

1. The performance of a client-server system is strongly influenced by two major network characteristics: the bandwidth of the network (that is, how many bits/sec it can transport) and the latency (that is, how many seconds it takes for the first bit to get from the client to the server). Give an example of a network that exhibits i) high bandwidth but also high latency, and ii) then give an example of one that has both low bandwidth and low latency. i) High bandwidth but also high latency: A transcontinental fiber link might have many gigabits/sec of bandwidth, but the latency will also be high due to the speed of light propagation over thousands of kilometers. Similarly, a satellite link may run at megabits/sec but have a high latency to... Continue reading "Understanding Network Characteristics and Protocols" »

Evolution of the iPhone

Released on June 29, 2007, the iPhone has seen multiple new hardware iterations with new iOS releases since.

User Interface and Connectivity

The user interface is built around the device's multi-touch screen, including a virtual keyboard. The iPhone has Wi-Fi and can connect to cellular networks.

Core iPhone Features

An iPhone can:

• Shoot video (standard feature from the iPhone 3GS)
• Take photos
• Play music
• Send and receive email
• Browse the web
• Send and receive text messages
• Follow GPS navigation
• Record notes
• Perform mathematical calculations
• Receive visual voicemail

Other functionality, such as video games, reference works, and social networking, can be enabled by downloading mobile apps.

The App Store Ecosystem

As of January 2017, Apple'... Continue reading "Evolution of the iPhone: Early Models & Capabilities" »