Computers aren't magic. They are machines that take input, process it using binary, and give us output.

IPO Model

Basics

Every computer follows this cycle:

INPUT
Data Goes In
PROCESS
Thinking Happens Here
MEMORY
Short Term Save
STORAGE
Long Term Save
OUTPUT
Results Come Out

Architecture

The "Brain" & Memory.

ROM (Boot Up)

Non-Volatile (Safe when off). Holds start-up instructions.

CPU (Processor)

Fetches, Decodes & Executes instructions. Speed in GHz.

RAM (The Desk)

Fast, Volatile (Lost when off). Holds open apps.

Storage (Cabinet)

Slow, Non-Volatile. Holds Files & Operating System.

Hardware Gallery

Input

  • Keyboard
  • Mouse
  • Mic
  • Webcam
  • Gamepad

Output

  • Monitor
  • Printer
  • Speaker
  • Phones
  • Projector

Storage

  • HDD
  • SSD
  • USB
  • DVD
  • Cloud

Specialist & Accessibility Hardware

Specialist Input

  • Braille Keyboard: For visually impaired users.
  • Puff-Sip Switch: Control via breath (paralysis).
  • Eye Tracker: Control mouse with eye movement.
  • Barcode Reader: Fast data entry (Shops).

Specialist Output

  • Braille Embosser: Prints raised dots for reading.
  • Screen Reader: Speaks text aloud (Blindness).
  • 3D Printer: Creates physical objects/parts.
  • Plotter: Prints huge high-quality diagrams.

Sensors (Auto-Input)

  • Light Sensor: Controls street lights / phone screen.
  • Thermostat: Measures temp (Central heating).
  • Motion Sensor: Detects movement (Alarms).
  • Gyroscope: Detects rotation (Gaming/Phone).

Binary Basics

Core
THE 8-BIT BYTE
128
64
32
16
8
4
2
1
0
0
0
0
0
0
0
0

Computers use switches: ON (1) & OFF (0)

Denary ⮕ Binary

Method: "Does it fit?"

Target: 20

  1. Does 128 fit in 20? No (0)
  2. Does 16 fit? Yes (1). 20 - 16 = 4 remaining.
  3. Does 4 fit? Yes (1). 4 - 4 = 0 remaining.
128
64
32
16
8
4
2
1
0
0
0
1
0
1
0
0

Binary ⮕ Denary

Method: "Add the Headers"

Binary: 00101001

Look for the 1s and add their column headers together.

128
64
32
16
8
4
2
1
0
0
1
0
1
0
0
1
32 + 8 + 1 = 41

Essentials & Mistakes

⚠ Direction Matters!

Place values start at 1 on the RIGHT.

128 ... 4 2 1   ✔ Correct
1 2 4 ... 128   ❌ Wrong
📏 Size Ladder
Bit: 1 or 0
Nibble: 4 bits
Byte: 8 bits
KB: 1000 Bytes
MB: 1000 KB
GB: 1000 MB

Tip: There are 10 types of people in the world: those who understand binary, and those who don't.