OGE Informatics flashcards
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33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Information
- Data that has been interpreted and reduces uncertainty in the receiver; it has properties such as reliability, completeness, relevance and value.
- Byte
- A unit of data equal to 8 bits, able to store one of 256 distinct values, such as a single character in a one-byte encoding.
- Discrete signal
- A signal that takes a finite set of values from a finite alphabet, as in digital data, in contrast to a continuous analog signal.
- Software
- The set of programs that control computer hardware, divided into system software, application software and programming tools.
- Powers of two
- Values 2^10 = 1024, 2^20 = 1 048 576 and 2^30, used because computing prefixes K, M and G usually mean powers of 1024.
- Hartley formula
- For N equally likely outcomes, one outcome carries i = log2 N bits; equivalently the number of messages equals 2^i.
- Binary to decimal
- Sum each digit multiplied by 2 raised to its position, positions counted from 0 at the rightmost digit.
- Hexadecimal digit
- One of the 16 symbols 0–9 and A–F, each encoding exactly 4 binary bits, which makes hex a compact form of binary.
- Image file size
- Volume equals width times height times bits per pixel, divided by 8 for bytes; colour depth determines bits per pixel.
- Number of codes
- The number of distinct binary words of length k is 2^k; over an alphabet of size n it is n^k.
- Model
- A substitute for a real object that preserves only the properties essential to the task, and may be material or informational.
- Algorithm
- A finite, precise sequence of steps that transforms input data into a result, possessing discreteness, determinacy, termination and mass character.
- Flowchart symbols
- Oval marks start and end, parallelogram marks input and output, rectangle marks a process, rhombus marks a decision condition.
- Loop with counter
- A loop whose body is executed a fixed number of times; for i from 1 to n inclusive it runs exactly n times.
- Branching algorithm
- An algorithm whose execution path depends on a condition, so one of two or more branches is chosen and executed.
- Mod operation
- The remainder after integer division; for positive a and b, a = (a div b) times b plus (a mod b).
- Variable
- A named memory cell whose type determines the values it may hold and the operations allowed on those values.
- Assignment statement
- A command that evaluates the expression on the right and stores the result in the variable on the left, replacing its old value.
- Boolean operator precedence
- In expressions, not is evaluated first, then and, then or; comparison operators produce True or False values.
- Swap with temporary
- Exchanging two variable values requires a third variable: t := a; a := b; b := t.
- Von Neumann architecture
- A computer design with a processor, memory and input/output devices, where program instructions and data share the same memory.
- File extension
- The part of a file name after the dot that indicates the data format and usually the program that opens the file.
- Volatile memory
- Memory such as RAM that loses its contents when power is switched off, unlike ROM and disk storage.
- File path
- The full address of a file: drive letter, then the chain of folders, then the file name, as in C:\SCHOOL\INFO\test.txt.
- IP address
- A numeric address identifying a device on a network; in IPv4 it is four numbers from 0 to 255 separated by dots.
- DNS
- The domain name system that translates a human-readable domain name into the numeric IP address of the server.
- Client-server model
- A scheme where a server stores resources and provides services while client computers send requests and receive responses.
- URL
- A uniform resource locator giving the protocol, server name and path to a file, such as https://site.ru/page.html.
- Transfer time
- The time to send a file equals its volume divided by the transfer rate, provided both use compatible units.
- Phishing
- A fraud technique using fake messages or look-alike sites that urge the user to reveal passwords or bank card data.
- Strong password
- A password of at least 8–12 characters mixing letters, digits and symbols, not a dictionary word, and unique per service.
- Absolute cell reference
- A spreadsheet reference such as $B$3 whose row and column stay fixed when the formula is copied to another cell.
- Database record
- One row of a database table, containing values for all fields and describing a single object; a key uniquely identifies it.