Information technology Notes
Section 1: Fundamentals of Hardware and Software
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1. What is a Computer?
A computer is an electronic machine that manipulates data according to a set of instructions called a program.
What is a Computer System?
A computer system includes:
· Hardware devices – the physical parts you can touch
· Software – the programs/instructions that make the computer function
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2. What Can a Computer System Do?
A computer system performs four basic operations:
Input – Accept data and instructions
Process – Process data according to instructions
Output – Produce results
Storage – Store data and results for future use
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3. Input Devices
Input devices allow data and instructions to be entered into the computer system.
Two Categories:
A. Manual Input Devices
You must enter or transfer data into the computer by hand.
Keyboard – Most common input device; used to enter data
Mouse – Handheld pointing device used to move cursor, click and select items
Joystick – Lever used mainly to control movement in games/simulations
Touch Screen – Display that also acts as input; interact by touching
Scanner – Converts printed documents/images into digital files
Voice Recognition – Converts spoken words into text or commands
B. Automated Data Entry Devices
Capture and enter data directly into the computer without human intervention.
Barcode Reader – Scans barcodes and sends coded data to computer
Optical Character Reader (OCR) – Scans printed/written text and converts to editable digital text
Magnetic Ink Character Recognition (MICR) – Reads special magnetic ink characters (bank cheques)
Optical Mark Recognition (OMR) – Detects pencil marks on forms (exam answer sheets)
Smart Card – Plastic card with embedded chip; stores data and handles authentication
Point of Sale (POS) – Used in shops to process sales, take payments, issue receipts
MIDI – Protocol letting digital musical instruments and computers exchange music data
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4. Output Devices
Output devices allow processed data to be made available to the user.
Types of Output:
A. Soft Copy Output (Temporary)
Information displayed on screen, in voice, or through speakers.
· Monitor
· Video Graphics Card
· Audio Output Devices
· Multimedia Projector
B. Hard Copy Output (Permanent/Tangible)
Information printed onto paper or film.
· All types of printers
· Plotter printer (draws large, precise drawings)
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5. Hardware Components of a Computer System
Computer systems consist of hardware components that work with software and peripheral devices to achieve specific tasks.
CPU (Central Processing Unit)
Found inside the system unit. Has two main parts:
ALU (Arithmetic Logic Unit) – Performs arithmetic and logic operations
CU (Control Unit) – Controls flow and execution of data and instructions
Peripheral Devices
Pieces of computer hardware connected to the computer (internal or external).
Examples: Keyboard, mouse, monitor, printer
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6. Primary Storage Devices
Used by the computer for its own use. Some hold data temporarily while working; others store data that doesn't change. Built from millions of bistable devices (can be set to 1 or 0).
Types of Primary Storage:
ROM (Read Only Memory) – Permanent storage; keeps data even when power is off; non-volatile
PROM (Programmable ROM) – Can be programmed once
EPROM (Erasable Programmable ROM) – Can be erased and reprogrammed
RAM (Random Access Memory) – Temporarily holds data CPU needs right now; volatile
RAM Types:
SRAM (Static RAM) – Fast, volatile cache memory; small MB; no permanent storage
DRAM (Dynamic RAM) – Volatile main memory; usually GB; loses data when power off
SDRAM (Synchronous DRAM) – Synchronized DRAM used as RAM; usually GB
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7. Secondary Storage
Computer hardware that records data to and retrieves data from a storage medium.
Floppy Disk – Thin magnetic disk for small files; 1.44 MB
Flash Drive – Small portable USB device using flash memory; 8 GB – 1 TB
Hard Disk – Magnetic storage with spinning platters; 500 GB – 20 TB
Magnetic Tape – Long magnetic ribbon for backups/archives; hundreds of GB – several TB
Flash Memory Cards – Small removable storage (cameras, phones); 8 GB – 1 TB
CD – Optical disc read by laser; ~700 MB
USB – Common plug and port standard for connecting devices
Cloud Storage – Online storage on remote servers; GB – TB
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8. Cloud Storage
Cloud storage is a method of saving digital data on remote servers accessed via the internet, rather than on a local hard drive.
Providers:
Google, Amazon, Microsoft, Apple, Dropbox, IDM, Oracle, Flow
Categories of Cloud Storage:
Public Cloud – Services offered over internet by third party; shared among many users. Examples: Google Drive, OneDrive, Amazon S3
Private Cloud – Dedicated to one organization for more control/security. Examples: AWS VMM, IBM Cloud Private
Hybrid Cloud – Mix of public and private; data/apps move between both. Examples: Netflix, Hulu, Uber, Airbnb
Advantages of Cloud Storage:
1. Buy as much or as little storage as needed
2. Cheaper — cost spread across many users
3. Data accessed from anywhere on any device
4. More secure — not lost if computer fails/is stolen
Disadvantages:
Data may be vulnerable to theft by hackers
Why is Cloud Storage Important?
Cost-effective, scalable storage. No worry about running out of capacity, no need to maintain SANs, replace failed devices, or add infrastructure.
Top 10 Cloud Storage Services:
1. Microsoft OneDrive
2. Google Drive
3. iDrive
4. Proton Drive
5. Dropbox
6. Apple iCloud
7. Mega
8. Sync.com
9. pCloud
10. Backblaze
Local Storage
Saving files/information/data directly on your device. Primary and secondary storage are forms of local storage.
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9. Types of Computers
Microcomputer – Laptop, tablet
Minicomputer – DEC PDP-8, HP 3000
Mainframe – IBM z16, Unisys
Supercomputer – Frontier, Fugaku
Classification by Size (Largest to Smallest):
1. Supercomputers
2. Mainframe Computers
3. Minicomputers
4. Personal Computers
Definitions:
Supercomputer – Powerful computer that processes large amounts of data and does great amounts of computation very quickly. Used in Science, Engineering, Education, Defence, Aerospace.
Mainframe Computer – Typically has monitor, keyboard, mouse, and tower (system unit).
Minicomputer – Mid-range computer; intermediate in size, power, speed, storage between mainframe and microcomputer.
Personal Computer – Small computer designed for use by a single user at a time. Uses a single chip (microprocessor) for its CPU.
· Portable personal computer
· Laptop/notebook — small enough to rest on user's lap; battery powered
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10. Historical Computing Devices
Abacus – Year 3000 BC – Manual counting tool using beads on rods/wires for arithmetic
Napier's Bones – Year 1617 – Set of rods with multiplication tables; simplified calculation by turning multiplication into addition
Pascaline – Year 1642 – First successful mechanical calculator using gears to add and subtract
Stepped Reckoner – Year 1672 – First calculator capable of all four
arithmetic operations
Leibniz Wheel – Year 1673 – Stepped drum gear mechanism inside Stepped Reckoner; used in mechanical calculators for centuries
Difference Engine – Year 1822 – Automatic mechanical calculator designed to compute and print math tables