Evolution & Generations of Computing
The Abacus used beads to add and subtract. Charles Babbage designed the first mechanical general-purpose computer (1837). Ada Lovelace wrote the first algorithm for it, making her the first computer programmer. Herman Hollerith's punch-card machine (1890) began the shift to data processing. Since then, computers have moved through five generations:
Room-sized machines
Magnetic drum memory, machine-language programming (0s & 1s). Examples: ENIAC, UNIVAC I, EDSAC.
Smaller & reliable
High-level languages COBOL & FORTRAN appear. Examples: IBM 1401, IBM 7090.
Operating systems arrive
Thousands of transistors on one chip. Multiple programs run at once. Example: IBM 360 series.
The personal computer
Intel 4004 (1971), GUI, PCs, laptops, internet. Examples: Apple II, IBM PC.
Beyond traditional computing
Artificial Intelligence, Parallel Processing, IoT, Quantum & DNA Computing.
Computer Organisation
Every computer — from a server to a smartphone — is built from the same functional units, following the Von Neumann architecture (1945): instructions and data share the same memory.
keyboard, mouse, scanner
CU + ALU + Registers
monitor, printer, speaker
The Storage Unit (RAM, ROM, HDD/SSD) sits alongside the CPU, feeding and receiving data from it.
Control Unit (CU)
The "traffic police" of the computer — directs data flow between units and interprets program instructions.
Arithmetic Logic Unit (ALU)
Performs all arithmetic (+ − × ÷) and logical comparisons (>, =, <). The decision-making component.
Registers
The CPU's smallest, fastest storage. Special-purpose (PC, IR, MAR, MBR) and general-purpose (AX, BX, CX, DX).
Memory Units
| Unit | Abbrev. | Size |
|---|---|---|
| Bit | b | 1 or 0 |
| Nibble | N | 4 bits |
| Byte | B | 8 bits |
| Kilobyte | KB | 1,024 bytes |
| Megabyte | MB | 1,024 KB |
| Gigabyte | GB | 1,024 MB |
| Terabyte | TB | 1,024 GB |
| Petabyte → Yottabyte | PB…YB | each 1,024 × the one before |
Primary Memory
RAM — fast, volatile, holds running programs. ROM — non-volatile, stores BIOS/firmware. Cache — tiny, ultra-fast memory between CPU and RAM (L1, L2, L3).
Secondary Memory
Non-volatile, larger capacity, slower. HDDs, SSDs (faster & more durable than HDD), USB drives, memory cards.
Microprocessor & Motherboard
A microprocessor packs the CPU's data-processing logic onto a single chip. Its performance is judged by three characteristics:
Word Length
Bits processed at once — 4-bit (Intel 4004) up to 64-bit (Intel Core i7, AMD Ryzen).
Clock Speed
Pulses per second, measured in GHz — how fast instructions execute.
Number of Cores
Independent processing units on one chip — Dual, Quad, Octa-core enable parallel work.
Moore's Law: transistor count on a chip doubles roughly every two years — SSI → MSI → LSI → VLSI → ULSI. Motherboard: the main circuit board that physically connects the processor, RAM/ROM, storage, I/O devices and expansion cards.
Software
Hardware is nothing without instructions. Software is broadly split by how it interacts with hardware:
● System Software
Manages the hardware and bridges it to applications.
- Operating System — memory, process, file & device management (Windows, Linux, Android, iOS)
- Utilities — antivirus, disk cleanup, backup, defragmenter
- Device Drivers — translate OS commands for printers, graphics cards, Wi-Fi
- Language Translators — Assembler, Compiler, Interpreter
● Application Software
Performs specific tasks for the user, sitting above system software.
- General-purpose — word processors, spreadsheets, browsers, DBMS
- Special-purpose — accounting, reservation, payroll, media players
Free & Open-Source vs Closed Source
| Feature | Open-Source | Closed-Source (Proprietary) |
|---|---|---|
| Source code | Open — view, study, modify | Kept secret by the company |
| Fixes | Global community, often rapid | Only the vendor can patch |
| Security | "Many eyes" — bugs found fast | Must trust the vendor |
| Customisation | High — change it yourself | Low — wait on the company |
| Examples | Linux, LibreOffice, GIMP, Firefox | Windows, MS Office, Photoshop |
Richard Stallman founded the Free Software Foundation (1985) and the GNU Project, championing four freedoms: run, study, redistribute, and modify software — "free" means freedom, not price.
Data, Information & Processing
Raw facts only become useful once organised. This is the ladder from data to wisdom:
Stages of Data Processing
Remember GIGO — Garbage In, Garbage Out: bad data at the preparation stage means unreliable information at the end.
Speed
Millions of instructions per second.
Accuracy
Minimal errors when given correct data.
Diligence
Works for hours without fatigue.
Storage
Holds vast volumes of data.
Automation
Runs tasks on its own once programmed.
Versatility
Handles many kinds of work across fields.
Green Computing & e-Waste
Green computing (Green IT) designs, uses and disposes of computers in an eco-friendly, energy-efficient way.
Energy Efficiency
Less power for devices & data centres.Eco-Friendly Materials
Biodegradable, recyclable components.Waste Reduction
Extend device lifespan.Responsible Disposal
Handle old equipment safely.✓ Safe Disposal
Reuse — donate working devices.
Recycle — certified facilities recover gold, silver, copper.
Take-back programmes — Apple, Dell, HP trade-ins.
✗ Unsafe Disposal
Land filling & incineration release toxins.
Acid baths pollute water sources.
Exporting e-waste to countries with weak regulation harms workers.
e-Waste contains valuable metals (gold, silver, copper, palladium) and hazardous substances (lead, mercury, cadmium, arsenic) — improper disposal contaminates soil and groundwater.
Quick Recap
Tap a question to reveal the answer.
Who is known as the "Father of the Computer" and who is the first programmer?
Charles Babbage (designed the Analytical Engine, 1837) is the Father of the Computer. Ada Lovelace, who wrote the first algorithm for it, is regarded as the first computer programmer.
What technology defines each of the five generations of computing?
1st: Vacuum tubes · 2nd: Transistors · 3rd: Integrated Circuits · 4th: Microprocessors · 5th: AI, Parallel Processing, Quantum & DNA Computing.
What is the difference between RAM and ROM?
RAM is fast, volatile primary memory that holds running programs and data (lost on power-off). ROM is non-volatile and stores permanent firmware like the BIOS needed to boot the computer.
What do CU and ALU do inside the CPU?
The Control Unit (CU) directs the flow of data between units and interprets instructions. The Arithmetic Logic Unit (ALU) performs arithmetic operations and logical comparisons.
Differentiate System Software and Application Software.
System software (e.g. an OS) manages hardware and lets application software run; a computer cannot function without it. Application software (e.g. a word processor) performs specific user tasks; a computer can still run without it.
What is GIGO in data processing?
"Garbage In, Garbage Out" — if the input data is inaccurate or poorly prepared, the resulting output/information will also be unreliable, no matter how good the processing is.
Name two safe and two unsafe methods of e-waste disposal.
Safe: Reuse (donate working devices) and Recycle (certified recycling facilities). Unsafe: Land filling and Incineration (or acid baths / illegal exporting).