CSE101: Introduction to Computer Science Flashcards

Introduction to Computer Science and Definition of a Computer

• A Computer is a device that:

  • Takes data from the user or other peripheral devices.

  • Computes or manipulates the data by following specific sets of instructions known as programs.

  • Provides output to the user.

• Computer Science (CS):

  • CS is defined as the study of processes that interact with data and that can be represented as data in the form of programs.

• Branches of Computer Science:

  • Software engineering

  • Algorithms and complexity

  • Architecture and organization

  • Computational science

  • Graphics and visual computing

  • Networking and communication

  • Operating systems

  • Parallel and distributed computing

  • Platform-based development

  • Security and information assurance

  • Programming languages

  • Human-computer interaction

  • Information management

  • Intelligent systems

The Importance and Demand of Computer Science

• Computers are utilized in virtually every aspect of modern life, including:

  • Agriculture: Precision farming and resource management.

  • Health Care: Patient data, diagnostics, and medical research.

  • Industry Automation: Manufacturing and assembly controlled by software.

  • Global Telecommunication: Connecting the world via networks.

  • Security and Law: Digital forensics and surveillance.

  • Finance and Banking: Electronic transactions and risk assessment.

  • Information and Resource Management System: Efficient organizational tracking.

  • Self-driving Vehicles and Virtual Reality: Advanced interactive technologies.

• Computers are significantly less prone to mistakes than humans, leading to the gradual displacement of manual human labor.

• The demand for expertise in Computer Science continues to increase globally.

How a Computer Works: Workflow and Architecture

• Simple Workflow Diagram:

  • Inputs: The data provided to the system.

  • Processing: The manipulation of data based on instructions.

  • Output: The resulting information presented to the user.

• Roles of the Units:

  • Input Unit: Takes data/information from the user and stores it in the form of digital data.

  • Processing Unit: Performs operations as per the instructions or program provided to the computer.

  • Output Unit: Delivers the results of the processing to the user.

• Basic Architecture Components:

  • Input Unit: Standard examples include the keyboard and mouse.

  • Storage Unit: Composed of Primary Storage (volatile) and Secondary Storage (non-volatile).

  • Central Processing Unit (CPU): Known as the "workhouse," it consists of the Control Unit (CU) and the Arithmetic and Logical Unit (ALU). It executes programs by performing operations on data.

  • Output Unit: Examples include monitors and printers.

• Data vs. Control Flow:

  • Data Flow: The path data takes from input through storage and the CPU to the output.

  • Control Flow: Signals sent from the Control Unit to manage the sequence of operations.

Operational Examples and Data Representation

• Arithmetic Operation Example (Addition):

  • Inputs: $x = 2$, $y = 4$

  • Processing: $z = x + y = 2 + 4 = 6$

  • Output: $6$

• Logical Operation Example (Comparison):

  • Inputs: $x = 2$, $y = 4$

  • Processing: If x > y then '$x$ is greater' else '$y$ is greater'.

  • Output: $4$ is greater

• Data Types Used in Computers:

  • Text: Characters and numbers.

  • Image: A $2D$ or $3D$ matrix of pixels.

  • Video: Motion pictures represented as a series of frames.

  • Audio: Voice or sound captured as wave data.

  • Graphic: Computer-generated imagery (e.g., graphs, PDFs, animations, $3D$ models, games).

Digital Encoding: ASCII and Imaging

• ASCII (American Standard Code for Information Interchange):

  • Standardized binary codes for characters. For example, the character 'H' is represented as $1001000$ and 'I' as $1001001$.

  • ASCII Reference Table Specifics: Uses $2^{7} = 128$ unique combinations.

  • Unicode: A more expansive standard using $2^{16}$ variations to accommodate more characters.

• Image Representation Types:

  • Black-white (Binary): Each pixel is represented by $0$ (Black) or $1$ (White).

  • Grayscale: Pixels range from $0$ to $255$, where $0$ is black and $255$ is white.

  • Color (RGB): Uses a combination of Red, Green, and Blue values. Example: $(255, 0, 0)$ is Red; $(255, 255, 255)$ is White; $(0, 0, 0)$ is Black.

  • Total color combinations: $256 \times 256 \times 256 = 16.78 \text{ Million RGB colors}$.

• Multimedia Data Rates:

  • Video: Dynamic motion typically recorded at $\text{30 fps}$ (frames per second).

  • HD Video Data Rate Formula: $(1920 \times 1080) \times (1 \times 8) \times 30$

  • Audio: Converts sound waves into electrical voltage which is then generated as binary data via a transducer through processes like Delta modulation.

Hardware vs. Software

• Hardware (The "What"):

  • Internal Hardware: Hardware enclosed within the computer casing (e.g., Processor, RAM, Hard disk).

  • External Hardware: Peripheral devices outside the casing (e.g., Keyboard, Mouse, Monitor, Speaker, Modem, Microphone, CD-ROM drive).

• Software (The "How"):

  • A set of instructions that tells the computer how to complete specific tasks.

  • System Software: Manages computer resources at a low level. Includes the Operating System, compilers, loaders, linkers, and debuggers.

  • Application Software: Programs designed for end-users, such as word processors, database systems, and spreadsheet programs.

Operating System (OS) and System Management

• Operating System: A collection of programs acting as a smart assistant that controls information flow and manages usage, storage, and access of data.

• OS Components:

  • OS Shell: Includes the User Interface (UI), which may be Command/Character-based (e.g., DOS, UNIX) or Graphical User Interface (GUI).

  • Kernel: Part of the program that remains in main memory while the computer is running to direct nonresident programs.

  • Device Drivers: Facilitate communication between hardware (I/O devices) and programs.

• Where is OS Stored?

  • Resides in secondary storage but is transferred to RAM during the booting process.

  • ROM (Read Only Memory): Non-volatile memory containing a "skeleton" OS to allow basic keyboard and drive usage before loading the full OS.

• Main OS Functions:

  • Task Management: Preparing and monitoring tasks for CPU processing.

  • Memory Management: Allocation of memory for tasks, virtual memory management, and cache management.

  • Device Management: Controlling data flow to and from I/O devices.

  • File and Data Management: Organizing how files are created, copied, and stored.

  • System Monitoring: Checking resources for error detection and recovery.

Advanced Software Concepts: Multitasking and Utilities

• Process: An instance of a running program with associated data.

• Task: The basic unit of processing controlled by the OS.

• Multitasking: Running multiple processes simultaneously by sharing CPU time blocks called CPU Time Slices. When a slice ends, the process state is saved (interrupted) so the CPU can move to the next process in the queue.

• Context Switching: The act of switching the CPU from one process/user to another, such as shifting from a word processor to a spreadsheet.

• Utility Programs:

  • Backup Utility: Creates duplicate data copies.

  • Data Recovery: Restores damaged/corrupted data.

  • Antivirus: Scans for and detects malicious viruses.

  • Data Compression: Removes redundant data to save storage space.

  • Disk Clean-up: Removes unnecessary files and corrects disk problems.

  • Fragmentation: The scattering of file portions across the disk.

  • Defragmenter Utility: Reorganizes files into contiguous blocks to improve access speed.

Program Design: Translators and Algorithms

• Development Software: Translates high-level language code (written by humans) into Machine Language (binary machine code/object program).

  • Compilers: Translate the entire source code into machine code in one single step (e.g., Java, C++).

  • Interpreters: Translate and execute code one statement at a time interactively (e.g., Python, GO, R).

• Algorithm: A sequence of finite instructions used for calculations and data processing.

• Algorithm Representation:

  • Pseudocode: A generic way of describing algorithms using syntax similar to coding. It can be Sequential (one after another) or Non-sequential (based on flow control/conditions).

  • Flowchart: A graphical representation of an algorithm using standard shapes.

Flowchart Shapes and Logic

• Standard Shapes:

  • Oval: Start or End of a program.

  • Rectangle: Denotes a calculation/processing step.

  • Parallelogram: Denotes Input or Output operations.

  • Circle: Connects different blocks of code.

  • Arrow: Denotes the flow of the program.

  • Rhombus/Diamond: Denotes a decision; one arrow enters, but two arrows exit (based on True/False conditions).

• Conditional Operators:

  • Equality: $==$

  • Inequality: $!=$

  • Comparison: <, >, <=, >=

  • Logical: NOT ($!$), AND (&&), OR ($||$)

• Loop Components in Flowcharts:

  • Initialization: Setting variables to track the loop.

  • Condition: The boolean expression check to see if the loop should continue.

  • Body: The set of actions repeated in each cycle.

  • Steps: Updating the variables to eventually satisfy the loop exit condition.

Summary of Programming Languages Mentioned

• C / C++ / C#

• Java

• Python

• R

• SQL / MySQL

• HTML

• PHP

• JavaScript