IT & Computers

Think of a computer as four layers stacked bottom to top: HARDWARE (CPU, memory, storage), OPERATING SYSTEM, APPLICATIONS, NETWORK. Any IT question lands on exactly one layer — a question about RAM versus ROM is layer one, about Linux is layer two, about phishing is layer four. Also fix the memory ladder once: bit → byte → kilobyte → megabyte → gigabyte → terabyte, each step 1024 of the one below.

• Bit, byte, kilo, mega, giga, tera.

  A bit is one binary digit, eight bits make a byte, and each step up multiplies by roughly a thousand. Any storage or speed question resolves once the ladder is fixed.

• Hardware you can drop on your foot; software you cannot.

  System software runs the machine (the operating system), application software does a user's job. Input, processing, storage and output describe every device, so a question naming an unfamiliar device is answerable by asking which of the four it does.

• 1One byte is eight bits; RAM is volatile working memory while ROM and disk storage are non-volatile.
• 2The Information Technology Act, 2000 is India's primary law on cybercrime and electronic records.
• 3The Unified Payments Interface is operated by the National Payments Corporation of India and enables instant bank-to-bank transfers.
• 4Artificial intelligence covers machine learning, where a system improves from data rather than from explicit programming.
• 5A blockchain is a distributed ledger in which records are chained cryptographically, making retrospective alteration detectable.
• 6Cloud computing delivers computing resources as a metered service over a network rather than from a machine you own.

• RAM is volatile working memory that empties when power goes off; ROM is non-volatile and keeps its contents.
• 1 byte = 8 bits; 1 kilobyte = 1024 bytes, and each higher unit is 1024 times the previous one.
• The CPU has three parts — arithmetic logic unit, control unit and registers; it is the part that actually executes instructions.
• Phishing tricks a user into revealing credentials, while a virus is malicious code that attaches to files — the first attacks the person, the second attacks the machine.
• The Information Technology Act, 2000 is India's principal law on cybercrime and electronic records.

• RAM is not storage in the everyday sense — it loses its contents when power is cut. Options calling it permanent memory are wrong.

• Lucent's Computer Book
• Objective Computer Awareness — Arihant
• India Year Book — Publications Division, Government of India

• NCERT textbooks (free PDFs)
• ISRO
• PIB — government press releases