Flashcards
Computer Science: Unit 1: Data Representation: Part 2: Data Storage
Cards in this deck (45)
- 11.3Data Storage
- 2Digital datawhen data is held in binary form
- 3Number Values: what can one byte of storage hold and what about larger numbers? *What are fractions?one byte of storage can hold binary numbers equivalent to 0-225 in denary
larger numbers- computer uses several bytes linked together
fractions - instead of using a dot link in denary, binary uses an extra byte of data to store the position of the point. Sometimes called floating point numbers - 4How is text stored in a computer?using a number code
Every letter of the alphabet is given a code number. There are different codes for capital letters vs. smaller letters and punctuation. - 5What does ASCII stand for and what is it?The basic character code
American Standard Code for Information Interchange
a coding system with a number code for every standard key board character. - 6What is Unicode and why was it created?an extended coding system which includes non-European alphabets
Unicode was created for different languages- and includes characters from different alphabets. - 7What are file formats/types?a different way of storing digital data are called formats. Different types of computer file use different data formats. a file usually ends with a 3 or 4 letter file extension that tells you what type of data is stored in the file. The computer must detect the file format to know what the numbers mean.
- 8What are some examples of file formats/types>.txt - text stored as ASCII code
.doc - holds text plus document formatting
.exe instructions which the computer can carry out/execute - 9What is digital?something that has a precise value that can be represented as a number.
eg: binary numbers - 10What are some examples of image file types?BMP
JPG
GIF
PNG
TIF - 11What are computer images made of? what does it stand for?PIXELS
PICture ELement - 12What does each pixel represent? What is it?one light on a screen/ one dot of ink
It is the smallest identifiable area of an image. Each pixel is a single color and is given a binary value to represent the color. - 13What is the software that makes images?graphic software
- 14What are the 2 most common methods used to store images in digital form?bitmap
vector graphics - 15What is resolution?the concentration of pixels within a specific area.
- 16What is monochrome?each pixel is either black or white and uses just on bit (1 or 0)
- 17How many colors are there for 1, 2, 3, 4 ,8 bits?1 - 2 colors
2 - 4
3-8
4-16
8-216 - 1byte - 18What is color depth?the number of bits per pixel
- 19How do you calculate file size?image resolution * color depth
divide by 8 to get in bits - 20What does PMB stand for What is PMB monochrome?Portable Bit Map
black and white map - 21What are bitmaps?a bitmap file stores the position and colour of every pixel that makes up an image. THe image is made of millions of pixels and colors of each pixel is stored using a number code and therefore, bitmap files have lots of data
- 22What are the advantages and disadvantages of bitmap files?adv. - Bitmap graphics are detailed, realistic images
Bitmap files are good for storing photographs and colorful art
Dis- when the bitmap image is expanded the computers makes all the pixels bigger so becomes pixelated
Bitmaps are large files - 23What is High resolution and low resolution?high - images are made of lots of very small pixels so look detailed
low -fewer, larger pixels (take up less storage/space) - 24What are Vector Graphics?a vector image is made of shapes constructed from lines. The computer stores mathematical formulas that tell it how to draw the shapes and lines. This is less information than storing every single pixel and is therefore a smaller file than a bitmap file
- 25What are the advantages and disadvantages of Vector graphics?adv. - smaller file than bitmap
sharp precise and simple
pixelation doesn't affect it/ expanding image/enlarging image
dis. - cannot store realistic colored photographs - 26What is metadata?data about data
- 27What is image metadata and what are the examples?information other than image data stored in a file
eg: color depth in bits per pixel
resolution
date created
author - 28What are the two types of ways to reduce file size?lossy compression
lossless compression - 29What is lossy compression?removes data permanently
tries to reconstruct an image without the missing data
much smaller file sizes but some loss of quality
reduction in file size with some loss of quality - 30What are the advantages and disadvantages of lossy compression?adv. - smaller files
quicker to send
good for internet
Dis. - editable data dumped
poor for editing
low resolution = poor printing - 31What is lossless Compression? What are the advantages and disadvantages?reduction in size of a data file with no loss of data quality.
adv.- no loss of quality
good for editing
dis - longer to send
larger file than lossy
&more - 32What are some Image flie types?BMP
JPG
GIF
PNG
TIF - 33What do these stand for: BMP JPG GIF PNG TIFBMP- Basic Metabolic Panel
JPG- Joint Photographic Experts Group
GIF- Graphic Interchange Format
PNG- Portable Network Graphics
TIF - Tagged Image File Format - 34What is a device that is a converter from analogue to digital converters?AC/DC or DC/AC - analogue to digital converters
- 35What are some methods to compress sound? 3use fewer channels (mono instead of stereo)
Reduce sample rate- record fewer sound changes per second
reduce bit depth- remove the highest and lowest sounds - 36How do you calculate file size for sound?file size = bit depth * number of samples
- 37What is resolution?the accuracy with which the wave height is measured.
The higher the resolution, the higher the accuracy. - 38What is lossy compression in sound? What are some of the file types?removes the sound (permanently) in the frequency ranges that we can't hear easily or that least affects the perceived playback quality. - leaves out some data - can affect sound quality
file types of lossy compression for sound:
JPG, GIF,MP3,MP4 - 39What is lossless compression in sound? What are some of the file types?leaves out repeated data and instead makes notes of how many times its repeated. Finds patterns in the original text, encodes each pattern in a dictionary
File types: PNG, TIF, SVG - 40What are some advantages of Compression? 5/6download speed increases - quicker to complete, reduces traffic over the internet, less chance of transmission error
data allowances are reduced
voice can be transmitted fast enough to keep up with speech
reduces space on disk/servers
enables better streaming of music and video - 41What is buffering?video or music streaming causes buffering if the download speed is slower than the play back speed
- 42What are some ways to compress video?reduce audio quality or number of audio channels
reduce image quality
reduce number of images per second - sample rate - 43make sure to know some common file standards and if the are lossy or lossless compressionJPG- lossy
GIF-lossy
MP3- lossy
PNG-lossless
FLAC or M4A- lossless - 44What does the device capacity =?How much data it can store.
- 45How do you calculate required capacity?Required capacity = number of files * size of a single file.
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- Computer Science GCSE (Unit 1) Flashcards on Computer Science: Unit 1: Data Representation: Part 2: Data Storage, created by HRYN red on 18/11/2019.
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- HRYN red · Nov 2019
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- Jul 1, 2020
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