Introduction to Computers
What is a computer?
A computer is an electronic machine that takes input, processes data, and produces output.
When did the first concept of computer start?
The concept began in the 19th century with mechanical computing ideas.
- Charles Babbage – proposed the Analytical Engine (1830s)
- Ada Lovelace – wrote the first algorithm
When was the digital computer invented/started?
Digital computers started in the 1930s–1940s.
- ENIAC (1945)
- Based on binary (0s and 1s)
Important figures in the origin of computers
- Charles Babbage – design of programmable machine
- Ada Lovelace – first programmer
- Alan Turing – concept of computation (Turing Machine)
- John von Neumann – stored-program architecture
Evolution of Computers
| Era | Time Period | Key Idea | Examples / Figures |
|---|---|---|---|
| Mechanical Era | 1800s | Non-electronic mechanical machines | Charles Babbage, Ada Lovelace |
| Electromechanical Era | Early 1900s | Mix of electrical + mechanical parts | Harvard Mark I |
| First Generation | 1940–1956 | Vacuum tubes used | ENIAC |
| Second Generation | 1956–1963 | Transistors replaced vacuum tubes | Smaller, faster, reliable |
| Third Generation | 1964–1971 | Integrated Circuits (ICs) | Multiple components on chips |
| Fourth Generation | 1971–present | Microprocessors | Intel 4004 |
| Fifth Generation | Present & future | AI and advanced computing | Machine learning, quantum computing |
What are digital computers made of?
Digital computers are made of electronic components that process binary data (0s and 1s).
CPU (Central Processing Unit) – processes data
Memory (RAM, storage) – stores data
Input devices – keyboard, mouse
Output devices – monitor, printer
Circuits (transistors, ICs) – basic building blocks
Difference between analog and digital computers
Analog computers use continuous data, while digital computers use discrete (binary) data.
Analog computers
Work with continuous signals (e.g., voltage)
Less precise
Example: speedometer
Digital computers
Work with binary (0 and 1)
More precise and reliable
Example: laptop, smartphone
What are transistors?
A transistor is a tiny electronic switch/amplifier used to control electrical signals in a computer.
What is it made of?
Transistors are made of semiconductor materials.
- Mainly Silicon
- Sometimes Germanium
- Doped with impurities to control current flow
Example: Transistor ON = 1, OFF = 0 (used in digital computers) ___
How computers function (how they process data)
Computers follow a cycle: input → process → output → storage.
- Input: data entered (keyboard, mouse, sensors)
- Processing: CPU manipulates data using instructions
- Storage: data saved in memory or disk
- Output: results shown (screen, printer, sound)
Inside the CPU:
- Control Unit (CU): directs operations
- Arithmetic Logic Unit (ALU): performs calculations and logic
- Memory: holds data temporarily (RAM)
Everything is done using electrical signals representing 0 and 1.
What are binary numbers?
Binary numbers are a base-2 number system using only 0 and 1.
- 0 = OFF, 1 = ON (electrical state)
- Example: 1101₂ = 13₁₀ (decimal)
Binary number metric prefixes (data sizes)
Used to measure digital storage:
- Bit = 1 binary digit (0 or 1)
- Byte = 8 bits
- Kilobyte (KB) = 1,024 bytes
- Megabyte (MB) = 1,024 KB
- Gigabyte (GB) = 1,024 MB
- Terabyte (TB) = 1,024 GB
- Petabyte (PB) = 1,024 TB
- Exabyte (EB) = 1,024 PB
- Zettabyte (ZB) = 1,024 EB
- Yottabyte (YB) = 1,024 ZB
- Brontobyte (BB) = 1,024 YB (theoretical/rare usage)
- Geopbyte (GBB) = 1,024 BB (theoretical)
- Attobyte = extremely small theoretical unit (below common storage scales, not practically used in computing systems)
Other number systems used in computers (with examples)
- Decimal (base-10) – human system
- Example: 45, 100
- Binary (base-2) – computer core system
- Example: 1011₂ = 11₁₀
- Octal (base-8) – shorthand for binary
- Example: 17₈ = 15₁₀
- Hexadecimal (base-16) – compact binary representation
- Uses 0–9 and A–F
- Example: A3₁₆ = 163₁₀
- Common in memory addresses and colors (e.g., #FF5733)