🧩 UNIT 1 — Computer Basics and Number Systems

 🌍 1.1 Generation of Computers

Computers have evolved drastically — from vacuum tubes to AI-powered processors. Each generation is marked by hardware technology, processing speed, and language level.

Generation	Years	Technology Used	Language Used	Example Computers	Features
1st Generation	1940–1956	Vacuum Tubes	Machine Language	ENIAC, UNIVAC	Large, slow, expensive, consumed a lot of power
2nd Generation	1956–1963	Transistors	Assembly Language	IBM 1401, CDC 1604	Faster, smaller, less heat, more reliable
3rd Generation	1964–1971	Integrated Circuits (ICs)	High-Level Languages (FORTRAN, COBOL)	IBM 360, PDP-8	Smaller, faster, multitasking possible
4th Generation	1971–1980s	Microprocessors (VLSI)	High-Level Languages (C, BASIC)	Intel 4004, Apple II	Personal computers introduced
5th Generation	1980s–Present	ULSI, AI, Parallel Processing	AI languages (Prolog, Python, ML)	IBM Watson, Quantum computers	AI, machine learning, natural language processing

🧠 Key Idea:
Each generation increased speed, reliability, miniaturization, and user-friendliness while reducing cost and power consumption.

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💻 1.2 Functional Block Diagram of a Computer

Every computer follows a simple structure known as the Von Neumann Architecture.

+--------------------------------------------+
|                USER INTERFACE              |
+--------------------------------------------+
| INPUT → CPU (ALU + CU + Registers) → OUTPUT |
|                 ↑          ↓                |
|              MEMORY (Primary + Secondary)  |
+--------------------------------------------+

1️⃣ Input Unit:
Takes data and instructions (e.g., keyboard, mouse, scanner).

2️⃣ Output Unit:
Displays results to the user (e.g., monitor, printer).

3️⃣ Memory Unit:
Stores data temporarily or permanently.

• Primary Memory: RAM, ROM

• Secondary Memory: Hard Disk, SSD

4️⃣ CPU (Central Processing Unit):

• ALU (Arithmetic Logic Unit): Performs calculations and logical operations.

• CU (Control Unit): Controls the flow of data and instruction execution.

• Registers: High-speed storage inside CPU for quick data access.

🧩 Flow:

Input → Process (CPU) → Output
          ↑
        Memory

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🧠 1.3 Hardware vs Software

Aspect	Hardware	Software
Definition	Physical components of a computer	Set of programs/instructions
Examples	Keyboard, CPU, Hard disk	OS, MS Word, Browser
Tangibility	Can be touched	Intangible
Failure	Hardware wears out	Software bugs
Dependency	Needs software to function	Runs on hardware

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💬 1.4 Types of Programming Languages

Type	Description	Example
Machine Language	Binary (0s and 1s), directly understood by computer	10110100 01100001
Assembly Language	Uses mnemonics for machine instructions	MOV A, B
High-Level Language	Human-readable, needs compiler/interpreter	C, Java, Python

Conversion Tools:

• Assembler: Assembly → Machine

• Compiler: High-Level → Machine (all at once)

• Interpreter: High-Level → Machine (line by line)

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🔢 1.5 Number Systems

System	Base	Digits Used	Example
Binary	2	0, 1	1011
Octal	8	0–7	27
Decimal	10	0–9	45
Hexadecimal	16	0–9, A–F	2F

Conversions:

• Binary → Decimal: Multiply each bit by 2ⁿ and sum.
  Example: 1011₂ = 1×8 + 0×4 + 1×2 + 1×1 = 11₁₀

• Decimal → Binary: Divide by 2 repeatedly and write remainders in reverse.
  Example: 13₁₀ → 1101₂

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➕ 1.6 Binary Arithmetic

Operation	Example	Result
Addition	101 + 10	111
Subtraction	101 – 10	11
Multiplication	101 × 10	1010
Division	1010 ÷ 10	101

Binary Addition Rules:

+	0	1
0	0	1
1	1	10 (carry 1)