NIELIT CCC cheat sheet

Computer generations: 1st vacuum tubes (ENIAC, 1946), 2nd transistors, 3rd integrated circuits, 4th microprocessors, 5th AI/ULSI.

Data units: 1 byte = 8 bits; 1 KB = 1024 bytes; 1 MB = 1024 KB; 1 GB = 1024 MB; 1 TB = 1024 GB.

CPU has three units: ALU (arithmetic/logic), Control Unit (fetch-decode-execute), and registers (fastest storage).

Memory hierarchy by speed: registers > cache > RAM > SSD/HDD > optical/magnetic tape.

RAM is volatile and holds active programs; ROM is non-volatile and holds firmware such as BIOS.

Input devices convert data into machine form (keyboard, mouse, scanner, mic); output devices present results (monitor, printer, speaker).

Software classes: system software (OS, drivers, utilities) vs application software (word processor, browser, games).

1 nibble = 4 bits; hexadecimal uses 4 bits per digit; octal uses 3 bits per digit.

Primary storage is directly accessed by CPU; secondary storage (HDD/SSD) is non-volatile and slower but larger.

OS functions: process management, memory management, file management, device management, and user interface provision.

Booting types: cold boot (from power-off) vs warm boot (restart); BIOS/UEFI runs POST before loading the OS kernel.

GUI vs CLI: GUI uses windows/icons/pointers; CLI accepts typed commands (e.g., Windows cmd, Linux bash).

Windows shortcuts: Ctrl+C copy, Ctrl+V paste, Ctrl+X cut, Ctrl+Z undo, Alt+Tab switch apps, Alt+F4 close window.

File path in Windows uses backslash C:\Folder\file.txt; Linux uses forward slash /home/user/file.txt.

A process is a program in execution; a thread is the smallest schedulable unit within a process.

Virtual memory uses disk space (swap/pagefile) to extend RAM; thrashing occurs when paging overwhelms real memory.

Common file extensions: .exe executable, .txt text, .docx Word, .xlsx Excel, .pptx PowerPoint, .pdf portable document.

File attributes include read-only, hidden, system, and archive; NTFS and FAT32 are Windows file systems.

Word shortcuts: Ctrl+B bold, Ctrl+I italic, Ctrl+U underline, Ctrl+S save, Ctrl+P print, Ctrl+F find, Ctrl+H replace.

Alignment options: left (Ctrl+L), center (Ctrl+E), right (Ctrl+R), justify (Ctrl+J).

Header/footer appear on every page; page numbers are inserted via Insert > Page Number.

Mail merge combines a main document with a data source (list of names/addresses) to produce personalized letters.

Find (Ctrl+F) locates text; Replace (Ctrl+H) substitutes occurrences, optionally with Match Case.

Track Changes records edits; Accept/Reject controls which revisions persist in the final document.

Table of Contents is generated automatically from heading styles; update fields with F9.

Page setup controls margins, orientation (portrait/landscape), paper size, and layout.

Word count displays characters, words, lines, and paragraphs of the current document or selection.

Cell reference types: relative A1 (adjusts on copy), absolute $A$1 (fixed), mixed $A1 or A$1 (partly fixed).

Formula always begins with = ; e.g., =A1+B1 adds cells; =SUM(A1:A10) totals a range.

Common functions: SUM, AVERAGE, COUNT, COUNTA, MAX, MIN, IF, VLOOKUP, ROUND.

IF syntax: =IF(condition, value_if_true, value_if_false) - e.g., =IF(A1>=40,"Pass","Fail").

VLOOKUP syntax: =VLOOKUP(lookup_value, table_array, col_index_num, [range_lookup]).

Error values: #DIV/0! divide by zero; #REF! invalid reference; #NAME? unrecognized name; #VALUE! wrong type.

Charts: column/bar compare categories; line shows trends over time; pie shows parts of a whole.

Sorting orders data by a key; filtering hides rows not matching criteria without deleting them.

Freeze Panes locks rows/columns in view; AutoFill extends patterns and formulas by dragging the fill handle.

PowerPoint shortcuts: F5 start slideshow from beginning; Shift+F5 start from current slide; Esc end show.

Slide layouts define placeholders (title, content, two content, blank); the Slide Master controls global formatting.

Transitions apply between slides; animations apply to individual objects within a slide.

Views: Normal (edit), Slide Sorter (reorder), Notes Page (speaker notes), Slide Show (present).

Insert options include pictures, charts, SmartArt, tables, audio, and video clips.

Design themes control fonts, colors, and backgrounds consistently across all slides.

Rehearse Timings records slide durations for automatic playback during a show.

Speaker notes are visible to the presenter but not to the audience during a slideshow.

Exporting to PDF or video preserves the presentation for sharing without PowerPoint.

Internet is a global network of networks; WWW is a hyperlinked information system that runs on the Internet.

Protocols: HTTP/HTTPS for web pages; FTP for file transfer; SMTP for sending mail; POP3/IMAP for receiving mail.

URL parts: protocol://domain/path - e.g., https://example.com/page.html.

IP addresses: IPv4 uses 32 bits (e.g., 192.168.1.1); IPv6 uses 128 bits in hexadecimal.

DNS resolves domain names to IP addresses; a browser caches results locally.

HTTP status codes: 200 OK, 301 Moved Permanently, 404 Not Found, 500 Internal Server Error.

Search operators: quotes for exact phrase, site: for domain restriction, minus sign to exclude terms.

Browsers include Chrome, Firefox, Edge, Safari; cookies store session state on the client.

HTTPS encrypts traffic via TLS; a padlock icon in the address bar indicates a secure connection.

Email address format: local-part@domain - e.g., [email protected]; the @ separates mailbox from domain.

Fields: To (primary recipients), Cc (visible copy), Bcc (hidden copy), Subject (topic line), Body (message).

Reply answers the sender; Reply All answers sender plus all Cc recipients; Forward resends to new recipients.

Attachments are files sent with a message; common limits are 10–25 MB per message depending on provider.

Common email protocols: SMTP for outbound, POP3 downloads and deletes from server, IMAP keeps mail synced on server.

Spam is unsolicited bulk mail; phishing is fraudulent mail that tricks users into revealing credentials.

Signature block auto-appends sender name, title, and contact details to every outgoing message.

Labels/folders organize mail; filters automatically route incoming messages based on rules.

Social networking sites (Facebook, X, LinkedIn, Instagram) enable profile creation, connections, and content sharing.

Privacy controls limit who can view posts, tag photos, or send friend requests; default settings are often public.

Digital footprint is the trail of data left online; it persists and can be searched by third parties.

Cyberbullying is harassment via digital channels; reporting and blocking tools mitigate harm.

e-Governance delivers government services electronically: online forms, certificates, tax filing, and payments.

Digital India pillars include broadband highways, universal mobile access, public internet access, and e-governance.

Aadhaar-based e-KYC and DigiLocker are examples of Indian e-governance digital identity and document services.

Two-factor authentication adds a second verification step (OTP, app code) beyond a password.

Strong passwords use length plus mixed case, digits, and symbols; reuse across sites increases breach risk.