UP Police Computer Operator cheat sheet

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

Von Neumann architecture: CPU (ALU + control unit + registers), memory, I/O, and buses; instructions and data share the same memory.

Cache hierarchy: L1 fastest and smallest, then L2, L3, then RAM, then secondary storage; SRAM is used for cache, DRAM for main memory.

ROM types: PROM (programmable once), EPROM (erase with UV light), EEPROM (electrically erasable); flash memory is a form of EEPROM.

Number systems: binary base 2, octal base 8, decimal base 10, hexadecimal base 16; 1 hex digit = 4 bits, 1 octal digit = 3 bits.

Two's complement: invert all bits and add 1 to get the negative; n-bit range is -2^(n-1) to 2^(n-1)-1.

Logic gates: AND (all 1s), OR (any 1), NOT (invert), NAND and NOR are universal gates; XOR outputs 1 when inputs differ.

Primary memory is volatile (RAM) or non-volatile (ROM); secondary storage (HDD, SSD, optical) is non-volatile and slower.

Input devices: keyboard, mouse, scanner, microphone, OMR, OCR, MICR, barcode reader; output: monitor, printer, plotter, speaker.

An OS manages processes, memory, files, devices, and provides a user interface; examples: Windows, Linux, macOS, Android, Unix.

Process states: new, ready, running, waiting (blocked), terminated; a context switch saves and restores process state.

Scheduling algorithms: FCFS, SJF (shortest job first), Round Robin (time quantum), Priority; SJF gives minimum average waiting time.

Deadlock conditions (Coffman): mutual exclusion, hold and wait, no preemption, circular wait; all four must hold for deadlock.

Paging divides memory into fixed-size pages and frames; segmentation uses variable-size logical segments; virtual memory uses demand paging.

Thrashing occurs when the system spends more time swapping pages than executing; increasing RAM or reducing multiprogramming helps.

File systems: FAT, NTFS, ext3/ext4; NTFS supports permissions, encryption (EFS), and journaling on Windows.

Linux commands: ls (list), cd (change directory), pwd (print working directory), mkdir, rm, cp, mv, chmod (permissions), ps (processes), kill.

Windows shortcuts: Ctrl+C copy, Ctrl+V paste, Ctrl+X cut, Ctrl+Z undo, Ctrl+Shift+Esc Task Manager, Alt+Tab switch apps, Win+L lock.

Word: Ctrl+B bold, Ctrl+I italic, Ctrl+U underline, Ctrl+S save, Ctrl+P print, Ctrl+F find, Ctrl+H replace; .docx is the default format.

Word: Mail Merge combines a main document with a data source (list or spreadsheet) to produce personalized letters, labels, or envelopes.

Excel: a cell reference like A1 is relative; $A$1 is absolute; A$1 fixes the row; $A1 fixes the column; formulas start with =.

Excel functions: SUM, AVERAGE, COUNT, COUNTA, IF, VLOOKUP, HLOOKUP, INDEX, MATCH, CONCATENATE, LEN, LEFT, RIGHT, MID, ROUND.

Excel errors: #DIV/0! division by zero, #N/A value not found, #REF! invalid reference, #VALUE! wrong data type, #NAME? unrecognized name.

PowerPoint: .pptx default; Slide Master controls global design; transitions are between slides, animations are within a slide; F5 starts slideshow.

Access objects: tables (data), queries (retrieve/filter), forms (data entry), reports (print output), macros, modules; .accdb is the default format.

Access: a primary key uniquely identifies each record; a foreign key links to a primary key in another table; relationships enforce referential integrity.

Common shortcuts: Ctrl+N new, Ctrl+O open, Ctrl+S save, Ctrl+Z undo, Ctrl+Y redo, Ctrl+A select all, F12 Save As in Office apps.

OSI layers (top to bottom): Application, Presentation, Session, Transport, Network, Data Link, Physical; TCP/IP merges the top three into Application.

TCP is connection-oriented and reliable; UDP is connectionless and faster; IP handles addressing and routing.

IPv4 is 32-bit (e.g., 192.168.1.1); IPv6 is 128-bit; private IPv4 ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.

Common ports: HTTP 80, HTTPS 443, FTP 21, SSH 22, Telnet 23, SMTP 25, DNS 53, POP3 110, IMAP 143, DHCP 67/68.

Topologies: star (central hub/switch), bus (single backbone), ring (token passing), mesh (most redundant), tree (hierarchical).

Devices: hub (Layer 1 broadcast), switch (Layer 2 MAC), router (Layer 3 IP), gateway (protocol translation), modem (modulation/demodulation).

DNS resolves domain names to IP addresses; DHCP assigns IP addresses automatically; NAT translates private to public IPs.

HTTP status codes: 200 OK, 301 Moved Permanently, 404 Not Found, 500 Internal Server Error; HTTPS adds TLS encryption.

Internet services: WWW, email (SMTP send, POP3/IMAP receive), FTP (file transfer), VoIP, search engines; URL = protocol://domain/path.

DBMS types: hierarchical (tree), network (graph), relational (tables), object-oriented; RDBMS uses tables with rows and columns.

Keys: primary key (unique, not null), candidate key, alternate key, foreign key (references another table), composite key (multiple columns).

Normalization: 1NF atomic values; 2NF no partial dependency on part of a composite key; 3NF no transitive dependency; BCNF stricter 3NF.

SQL categories: DDL (CREATE, ALTER, DROP, TRUNCATE), DML (INSERT, UPDATE, DELETE), DQL (SELECT), DCL (GRANT, REVOKE), TCL (COMMIT, ROLLBACK).

SELECT syntax: SELECT columns FROM table WHERE condition GROUP BY columns HAVING condition ORDER BY columns [ASC|DESC] LIMIT n.

Joins: INNER (matching rows), LEFT (all left + matches), RIGHT (all right + matches), FULL (all rows), CROSS (Cartesian product).

Aggregate functions: COUNT, SUM, AVG, MIN, MAX; WHERE filters rows before grouping, HAVING filters groups after GROUP BY.

ACID properties: Atomicity, Consistency, Isolation, Durability; these ensure reliable transaction processing.

C data types: int (usually 4 bytes), char (1 byte), float (4 bytes), double (8 bytes), void; sizeof operator returns size in bytes.

C operators: arithmetic (+ - * / %), relational (== != < > <= >=), logical (&& || !), bitwise (& | ^ ~ << >>), increment/decrement (++ --).

Control flow: if-else, switch-case (with break), for, while, do-while (executes at least once); break exits loop, continue skips iteration.

C functions: declaration (prototype), definition, call; pass by value copies, pass by reference uses pointers; recursion calls itself with a base case.

Arrays: contiguous memory, index starts at 0; strings in C are char arrays ending with '\0'; strlen excludes the null terminator.

Pointers store memory addresses; * dereferences, & gives address; pointer arithmetic depends on the pointed type size.

C++ adds classes, objects, inheritance, polymorphism, encapsulation, and abstraction; cin >> input, cout << output, #include .

Java: platform-independent via JVM bytecode; class name and file name must match; public static void main(String[] args) is the entry point.

Java OOP: class (blueprint), object (instance), constructor (same name as class, no return type), this keyword, new operator allocates memory.

CIA triad: Confidentiality (secrecy), Integrity (accuracy), Availability (accessible when needed); these are core security goals.

Malware types: virus (attaches to files), worm (self-replicates over networks), trojan (disguised as legitimate), ransomware (encrypts and demands payment), spyware (collects data).

Encryption: symmetric uses one shared key (AES, DES); asymmetric uses public and private keys (RSA); hashing (SHA-256, MD5) is one-way for integrity.

Authentication factors: something you know (password), something you have (OTP token), something you are (biometrics); MFA combines two or more.

Cyber law in India: IT Act 2000 (amended 2008) governs electronic records, digital signatures, and cyber offences; DPDP Act 2023 protects personal data.

IT Act sections: 66 (computer-related offences), 66C (identity theft), 66D (cheating by personation), 66E (privacy violation), 67 (obscene material), 72 (breach of confidentiality).

Digital forensics: identify, preserve, acquire, examine, analyse, and report; maintain chain of custody; use write blockers to avoid altering evidence.

Common attacks: phishing (fake messages), SQL injection (malicious SQL), DoS/DDoS (flood traffic), man-in-the-middle (intercept), brute force (try all passwords).

UP Police motto: "Serving with sensitivity, committed to security" (सजग सेवा, सुरक्षा के लिए प्रतिबद्ध); headquarters at Lucknow.

UP Director General of Police (DGP) heads the state police; zones are headed by ADG/IG rank officers; districts by SP/SSP.

UP Police recruitment is conducted by the UP Police Recruitment and Promotion Board (UPPRPB), Lucknow; constable and SI exams are computer-based.

Uttar Pradesh has 75 districts and 18 divisions; official language is Hindi; capital is Lucknow; high court at Prayagraj (Allahabad).

UP Police emergency number is 112 (national emergency), 100 for police, 101 for fire, 108 for ambulance; UP 112 is the state emergency response system.

Important UP Police units: PAC (Provincial Armed Constabulary), STF (Special Task Force), Anti-Terrorism Squad (ATS), CBCID, Traffic Police.

Current affairs: track central and state government schemes, appointments, sports, awards, and UP-specific initiatives; dates and names are commonly asked.

Indian Constitution: police and public order are State List subjects (Entry 1 and 2, List II); the UP Police Act 1861 still governs policing in UP.

Hindi grammar: संज्ञा (noun), सर्वनाम (pronoun), विशेषण (adjective), क्रिया (verb), क्रियाविशेषण (adverb), संधि (junction), समास (compound).

Hindi sandhi types: स्वर संधि, व्यंजन संधि, विसर्ग संधि; examples: राम + अवतार = रामावतार (दीर्घ संधि).

Hindi samas types: तत्पुरुष, कर्मधारय, द्विगु, द्वंद्व, बहुव्रीहि, अव्ययीभाव; identify by the relation between the words.

Hindi synonyms (पर्यायवाची), antonyms (विलोम), idioms (मुहावरे), and proverbs (लोकोक्तियाँ) are frequently tested; learn common examples.

English parts of speech: noun, pronoun, verb, adjective, adverb, preposition, conjunction, interjection; identify by function in the sentence.

English tenses: simple present, present continuous, present perfect, simple past, past continuous, past perfect, future forms; match time markers.

Active to passive: object becomes subject, verb becomes be + past participle, subject becomes by-agent; e.g., "She writes a letter" → "A letter is written by her."

Direct to indirect speech: change pronouns, tense (backshift), and time/place words; use that for statements, if/whether for yes-no questions.

Common error areas: subject-verb agreement, articles (a/an/the), prepositions, and parallelism; read the full sentence before choosing.

Percentage: x% of N = (x/100) × N; percentage change = (new − old)/old × 100; successive change a% then b% = a + b + ab/100.

Profit and loss: Profit = SP − CP; Profit% = (Profit/CP) × 100; Loss% = (Loss/CP) × 100; SP = CP × (100 + Profit%)/100.

Simple interest: SI = P × R × T / 100; Compound interest: A = P(1 + R/100)^T; CI = A − P.

Time, speed, distance: Distance = Speed × Time; average speed = total distance / total time; 1 km/h = 5/18 m/s.

Ratio and proportion: if a:b = c:d then ad = bc; partnership profit shares are proportional to capital × time.

Averages: Average = sum of values / number of values; if each value increases by x, average increases by x.

Reasoning: series (arithmetic, geometric, square, cube, alternating), analogy (relation between pairs), classification (odd one out), coding-decoding (letter shifts).

Blood relations and direction sense: draw a diagram; for directions, use N, S, E, W and turns (left/right) to trace the final position.

Permutation and combination: nPr = n!/(n−r)!; nCr = n!/[r!(n−r)!]; probability = favourable outcomes / total outcomes.