History of Computers

• A computer is a programmable electronic device for processing, storing, and manipulating data.
• The term "computer" comes from the Latin word "computare," meaning "to calculate."
• The acronym for "computer" stands for Common Operating Machine Purposely Used for Technological and Educational Research, which is a myth rather than an official definition.
• The common acronym is not universally accepted in technical literature.

Father of Computer

• Charles Babbage is known as the "Father of the Computer."
• Babbage designed the Analytical Engine in the 1830s, a mechanical general-purpose computing device.
• Babbage's designs laid the groundwork for future computing developments, despite the Analytical Engine never being fully built during his lifetime.

Father of Modern Computer

• Alan Turing is often referred to as the "Father of the Modern Computer."
• Turing's work in the 1930s and 1940s, particularly his concept of the Turing machine, developed a theoretical framework for computers.
• Turing played a role in World War II by designing machines the cracked the German Enigma code.
• The title of "Father of the Modern Computer" isn't universally exclusive to Turing.

Generations of Computers

• First Generation (1940-1956) used vacuum tubes, resulting in large size and high power consumption.
• Second Generation (1956-1963) used transistors, making computers smaller, more reliable, and produced less heat.
• Third Generation (1964-1971) used integrated circuits, making computers faster, smaller, and more efficient.
• Fourth Generation (1971-Present) used microprocessors, leading to personal computers and user-friendly interfaces.
• Fifth Generation (Present-Future) uses AI hardware and quantum computing, focusing on advanced AI capabilities.

First Computer

• The first computer is often attributed to the ENIAC (Electronic Numerical Integrator and Computer), developed in the early 1940s.
• The ENIAC was developed by John W. Mauchly and J. Presper Eckert at the University of Pennsylvania's Moore School of Electrical Engineering.
• Completed in 1945, ENIAC became operational in 1946.
• ENIAC used 18,000 vacuum tubes, the primary technology of the first generation of computers.
• It was initially designed for military calculations like artillery trajectory and atomic bomb development.
• ENIAC was a general-purpose computer but could only execute one instruction at a time.
• Input was through punched cards, and created output to on printouts.
• It occupied about 1,800 square feet and weighed nearly 30 tons.

Functions of a Computer

• Input: Information or data entered into the computer sent to in the CPU
• Processing: The sequence of actions on data to convert them it into meaningful information.
• Output: Makes Processed data available to the user, mainly used to display results.
• Storage: Stores data and programs permanently, used for storing information during program execution, and enables info retrieval.

Input Unit

• The input unit enables data and instruction from to users to be provided the system.
• Serves as an interface between the external environment and the computer to allow interaction and data entry

Commonly used Input Devices

• Keyboard: The primary device for typing text, numbers, letters, and special characters for data entry and commands.
• Mouse: It allows users to navigate the graphical user interface (GUI) using buttons and a scroll wheel for clicking, dragging, and scrolling.
• Touchpad: A built-in alternative to a mouse on laptops that allows cursor control by moving fingers across a flat surface.
• Scanner: Converts physical documents and images into digital formats for storage or editing.
• Microphone: Captures audio input, converting sound waves into electrical signals for recording or communication.
• Webcam: A digital camera that captures video and images for video conferencing and streaming.
• Touch Screen: Allows users to interact directly with the displayed screen content, eliminating the need for a mouse or keyboard.
• Joystick: Used for gaming, this device controls movement in games and simulations.
• Barcode Reader: An optical scanner that reads barcodes, commonly used in retail for scanning product information.

Output Unit

• The output unit makes data become in a human-readable form.
• Output devices facilitate user-computer interaction by presenting data visually, audibly, or in print.

Common Types of Output Devices

• Visual Output Devices:
• Monitor: Displays images, videos, and text using LCD or LED technology for high-resolution visuals; also known as Visual Display Unit (VDU).
• Projector: Projects images and videos onto larger surfaces for presentations or entertainment.
• Print Output Devices:
• Printer: Produces physical copies of documents and images
  • Inkjet Printers use liquid ink to create images on paper.
  • Laser Printers: Use laser technology for high-quality prints at a fast speed.
  • Dot Matrix Printers: An older technology with print heads that strike an ink ribbon against paper.
• Audio Output Devices:
• Speakers: Convert digital audio signals into sound for users to hear music, notifications, and other outputs.
• Headphones: Provide personal audio output directly to the user.
• Specialized Output Devices:
• Plotter: Used for printing large-scale graphics and designs, such as architectural blueprints.
• Braille Embosser: Converts text into Braille for visually impaired users.
• 3D Printer: Creates three-dimensional objects from digital models by layering materials.

CPU

• The Central Processing Unit (CPU) which is known as the central processor, main processor, or simply processor, executes instructions from software and completes calculations.
• The CPU acts as the computer's control center, coordinating the activities of all components.

Components of CPU

• Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
• Control Unit (CU): Directs operations within the CPU.
• Registers: Hold temporary data and instructions.
• Cache Memory: Provides fast access to frequently used data.
• Memory Management Unit (MMU): Manages data flow between RAM and CPU.

ALU

• Performs all arithmetic operations involving (addition, subtraction, multiplication, and division) and logical operations, including comparisons.
• It executes mathematical calculations required by programs.

Control Unit

• Directs CPU operation by fetching instructions from memory, decoding them, and executing them by coordinating ALU actions.
• It manages data flow within the CPU.

Memory Management Unit (MMU)

• MMU manages data flow between the CPU and RAM by handling address translation, converting virtual addresses into physical addresses in RAM.
• It provides memory protection, which ensures processes do not interfere with each other's memory spaces.
• It is typically between the CPU and RAM, or integrated onto the CPU chip in modern CPUs.

Memory Unit (MU)

• The term "memory unit" generally refers to any storage component in a computer system that focuses on RAM where data is temporarily stored
• MU encompasses a broader range of memory types without the specific management functionalities provided by the MMU.
• The Main memory (RAM) itself which is physically separate from the CPU and connects to the CPU via the system bus.

Primary Storage

• Primary storage, also called main or internal memory, temporarily holds data, programs, and instructions in use.
• It is directly accessible by the CPU, enabling fast read and write operations essential for processing.

Features of Primary Storage

• Volatile Nature: Primary storage typically loses its contents when power is turned off.
• Random Access Memory (RAM) is used for storing data the CPU accesses quickly.
• Cache Memory: A smaller, faster volatile memory is located inside or close to the CPU to speed up data access.
• Non-Volatile Types: Primary storage can be non-volatile.
• Read-Only Memory (ROM): stores critical startup instructions and data that do not change.

Random Access Memory (RAM)

• RAM is volatile memory, so it loses its contents when off.
• It is used for temporary storage of data and programs currently in use.
• Dynamic RAM (DRAM) - the main type:
• It requires constant refreshing to maintain data and is commonly used as the main memory.
• Static RAM (SRAM):
• There is no need for refreshing as the the data is retained data as long as power is available.
• It is faster than DRAM but more expensive, so it is used for cache memory.

Read-Only Memory (ROM)

• ROM is non-volatile memory that retains its contents, even when the power is off to store firmware and system-level instructions.
• Programmable ROM (PROM): It can be programmed once after manufacturing.
• Erasable Programmable ROM (EPROM): It can be erased using UV light and reprogrammed.
• Electrically Erasable Programmable ROM (EEPROM): It can be electrically erased and reprogrammed, allowing multiple programming cycles.

Summary of Primary Storage

• RAM - Fast, temporary storage for active data. Volatile
• DRAM - Needs refreshing, commonly used. Volatile
• SRAM - No refreshing needed, faster but more expensive. Volatile
• ROM - Non-volatile, stores firmware. Non-volatile
• PROM - Programmable once. Non-volatile
• EPROM - Erasable by UV light. Non-volatile
• EEPROM - Electrically erasable. Non-volatile
• Cache Memory - High-speed memory for frequently accessed data. Volatile

VRAM and GPU

• VRAM is memory specifically designed for storing graphical data such as textures, frame buffers, and images for the GPU.
• It is optimized for high bandwidth and quick access to facilitate smooth rendering of images.
• A specialized processor GPU accelerates the rendering of images by performing complex calculations for graphics processing (rendering 3D graphics and video playback).
• The GPU utilizes VRAM to store processed data.

Feature of Single-Ported and Dual-Ported RAM

• Single-Ported RAM:

  • Access is one operation at a time.
  • Limited bandwidth, potential bottlenecks.
  • Simpler design
  • General applications

• Dual-Ported RAM:

  • Simultaneous read/write operations
  • Higher bandwidth, reduced latency.
  • More complex due to dual access control
  • Multi-processor systems, graphics processing (e.g., VRAM)

Secondary Storage

• Secondary storage is also known as auxiliary/external memory. It provides non-volatile and long-term for computer systems.
• Unlike primary storage (RAM), secondary storage retains data when the system is powered down.

Key Features of Secondary Storage

• Non-Volatile: Retains data permanently until data is deleted or overwritten, whether the computer is turned off or has power
• Larger Capacity: Larger storage capacities compared to primary storage, to hold documents, multimedia files, and applications.
• Slower Access Speed: It features Slower read and write speeds compared to primary storage because of the indirect access through input/output channels.
• Cost-Effective: Less expensive per unit of storage than primary storage options, making it economical for extensive data storage.

Types of Secondary Storage Devices

• Magnetic Storage devices:

• Hard Disk Drives (HDDs): Used for storing large amounts of data.

• Floppy Disks: It represents an older form of magnetic storage that is obsolete.

• Solid-State Drives (SSDs):

• It uses flash memory for faster access speeds and greater reliability than HDDs.

• Optical Storage:

  • CDs, DVDs, and Blu-ray Discs are used for media distribution and archiving data.

• External Storage Devices:

  • USB Flash Drives: Portable devices used for transferring and storing data.
  • External Hard Drives: Provide additional storage capacity and are used for backups.

• Cloud Storage: Allows users to save and access data on remote servers via the Internet, enabling sharing and accessibility from multiple devices.

Bus

• A bus is a communication system in a computer that transfers data between components like the CPU, memory, and peripheral devices.
• It serves as a pathway for effective data transfer between different computer parts.

Types of Buses

• Address Bus:

  • Carries information about memory addresses for reading or writing data.
  • Unidirectional: Carries signals from the CPU to memory.
  • The width determines the unique addresses accessed (e.g., a 32-bit address bus can address over 4 billion locations).

• Data Bus:

  • Carries data between the CPU, memory, and I/O devices.
  • Bidirectional: Data can flow in both directions.
  • The width determines data transferred simultaneously (e.g., a 64-bit data bus can transfer 64 bits at once).

• Control Bus:

  • Carries control signals from the CPU to other components to manage operations.
  • Includes timing and control signals to ensure smooth data transfers.
  • Conveys commands and status information between the CPU and peripheral devices.

Additional Types of Buses

• System Bus: Is a combination of the data bus, address bus, and control bus that connects the CPU to the main memory and other components on the motherboard.
• Internal Bus: Connects components within the computer, such as the CPU and RAM.
• External Bus: Connects external devices to the computer, such as USB ports and other peripheral connections.
• Expansion Bus: Allows additional cards/devices to be connected to the motherboard (e.g., PCI or PCIe buses).

Types of Buses Function and Directionality

• Data Bus: Carries actual data. Bidirectional
• Address Bus: Carries memory addresses. Unidirectional
• Control Bus: Carries control signals. Bidirectional
• System Bus: Combination of data, address, and control buses. N/A
• Internal Bus: Connects internal components. N/A
• External Bus: Connects external devices. N/A
• Expansion Bus: Connects expansion cards. N/A

50 Years Of Email

• 1971: Ray Tomlinson found a way to send mail to addresses over ARPANET to different computers.
• 1978: Gary Thuerk sent a marketing email to sell computers; this email became the first spam email ever recorded.
• 1988: The first commercially available email client was released by Microsoft, called 'MSMail'.
• 1993: It became possible to access emails anytime through web-mail clients
• 1997: Microsoft acquired Hotmail and later replaced it with Outlook in 2011.
• 2002: Email was now available on mobile devices such as Blackberry.
• 2003: Rules like making it compulsory to provide a way to unsubscribe from emails came into play.
• 2018: Gmail has since become the most popular email platform with plugins and enhanced capabilities since launching in 2004.

Practice Questions

• The process of arranging data in logical sequence is called Sorting
• 8 bits are equal to one byte
• Vacuum tubes were in the first generation of computers
• The first computer released available for commercial use was UNIVAC
• Computers process binary numbers, which are composed of 0 and 1