Computer Architecture Basics

Registers

• Accumulator: Stores temporary results during arithmetic and logical operations.
• Memory Address Register (MAR): Holds the memory address of the location to be accessed (read or written to).
• Memory Buffer Register (MBR): Temporarily stores data being transferred between the processor and memory.
• Instruction Register (IR): Contains the currently executing instruction.
• Program Counter (PC): Stores the memory address of the next instruction to be executed.

Memory Units

• Bit: Basic unit of data storage, represents a 0 or 1.
• Nibble: 4 bits.
• Byte: 8 bits.
• Kilobyte (KB): 1024 bytes.
• Megabyte (MB): 1024 KB.
• Gigabyte (GB): 1024 MB.
• Terabyte (TB): 1024 GB.
• Petabyte (PB): 1024 TB.

RAM vs ROM

• RAM (Random Access Memory): Volatile memory, used for storing data, instructions, and intermediate results. Accessed by the CPU quickly but data is lost when the power is off.
• ROM (Read Only Memory): Non-volatile memory, holds instructions for the computer's startup procedure. Data is retained even when power is off.

Cache Memory

• Cache: Small, high-speed memory between the CPU and RAM. Stores frequently accessed data and instructions for faster access.

Storage Units

• Primary Storage: Main memory (RAM and ROM). Has high access speed but limited capacity.
• Secondary Storage: Auxiliary memory (hard drive, CDs, DVDs, flash drives). Stores data permanently, has large capacity, and slower access speed.

Input Devices

• Keyboard: Used to input text, numbers, and symbols.
• Mouse: Navigates the computer screen by controlling the cursor/pointer.
• Light Pen: Pointing device that allows drawing directly on a display screen.
• Touch Screen: Allows user interaction by touching the display screen.
• Graphic Tablet: Similar to a digital notepad, used for creating images with a pen.
• Joystick: Used for gaming, controlling simulators, and robots.
• Microphone: Converts analog sound into digital format.
• Scanner: Captures images or text and converts them into digital format.
• OMR (Optical Mark Recognition): Reads marks on printed forms for data entry.
• Bar Code Reader: Reads barcodes to input data.
• QR Code Reader: Reads two-dimensional QR codes using a smartphone camera.
• Biometric Sensor: Identifies users based on unique physical characteristics (fingerprints, iris patterns, etc.).
• Smart Card Reader: Accesses data stored on smart cards, used in several applications.
• Digital Camera: Captures pictures and videos in digital format.

Output Devices

• Monitor: Displays visual information. Examples: CRT, LCD, TFT, LED, OLED.
• LCD Projector: Projects images or data onto a larger screen.
• Printer: Produces hardcopy output (printouts). Examples: Dot Matrix, Inkjet, Laser, Thermal.

Software Classifications

• Machine Language: Uses binary code (0s and 1s) that the computer directly understands.
• Assembly Language: Uses mnemonics (symbolic names) for instructions, making it easier to understand than machine language but still requires programming expertise.
• High Level Languages: Similar to human language, easier to learn and use, requires translation into machine language. Examples: Python, Java, C++, C#.
• Language Processors: Programs that translate code written in high-level languages or assembly language into machine language.
  • Assembler: Translates assembly language to machine language.
  • Interpreter: Converts high-level language code line by line.
  • Compiler: Translates a complete program written in a high-level language into machine language.
• Utility Software: Helps with system maintenance tasks. Examples: Compression tools, Disk Defragmenter, Backup Software, Antivirus Software.
• General Purpose Software: Designed to perform specific tasks in various application areas. Examples: Word Processors, Spreadsheet Software, Presentation Software, Database Software, Multimedia Software.
  • Word Processing Software: Creates and edits documents, formats text, checks spelling and grammar. Examples: MS Word, OpenOffice Writer, Apple Pages.
  • Spreadsheet Software: Performs calculations on numerical data, creates charts and graphs. Examples: Microsoft Excel, OpenOffice Calc, Lotus 1-2-3, Apple Numbers.
  • Presentation Software: Creates slideshows with text, images, animations, videos, and sound. Examples: Microsoft PowerPoint, Apple Keynote, OpenOffice Impress.
  • Database Software: Organizes, stores, and manages data in tabular format. Examples: Microsoft Access, Oracle, PostgreSQL, MySQL.
  • Multimedia Software: Integrates various types of media (text, graphics, audio, video). Examples: VLC Player, Adobe Flash, Real Player, Media Player.

Open Source vs Freeware vs Shareware

• Free and Open Source Software: Users have four freedoms: to run the software for any purpose; to study how it works and adapt it; to distribute copies; and to improve the software and release those improvements to the public.
• Freeware: Software that is available to use free of charge. Developers retain rights to the software.
• Shareware: Trial versions of the software that can be used for a limited period. Users need to pay if they wish to continue using the software.

E-Waste

• Electronic waste (e-waste) consists of discarded electronic devices like computers, phones, televisions, etc. It is becoming a serious global problem as it contains hazardous materials that can harm the environment and human health if disposed of improperly.

E-Waste Disposal

• Reuse: Reusing old devices for different purposes reduces waste generation.
• Recycling: Disassembling old devices for valuable components.
• Landfilling: Burying old devices directly, creating a harmful source of pollution.
• Incineration: Burning old devices releasing toxic fumes into the environment.