Flashcards
computer science
Flashcards do conjunto (63)
- 1what does ASCII stand forAmerican Standard Code for Information Interchange
- 2what is ASCIIASCII consists of 128 characters that are used in a computer. this is done in a seven bit binary with the 8th bit being a parity check and a character is represented using a character set
- 3parity checkwhen the 8 bit in binary is used to determine if the binary code is damaged or not.
equal numbers of 1 and 0 means the parity will be even
odd numbers of 1 and 0 means the parity will be uneven - 4character seta character set is a list or characters and codes used to represent a ASCII character
- 5what is UnicodeUnicode is the extended version of 256 characters that is enough for the English language but not international use
it uses 8 to 32 bits for each character. the characters can represent 2(16) - 6what are the two types of imagesvector and bitmap
- 7what is a bitmap imagea image made up from pixels
zooming in will reduce the quality of the photo - 8what is a vector imagea image made up of
lines,shapes and colour
zooming in wont decrease the quality of the photo - 9how is a bitmap image madea bitmap image is made up from rows of dots and pixels
each pixel or dot is made up from a binary bit - 10what does resolution meanthe quality or detail of a photo
- 11how can resolution be measured byimage size
and
pixels per inch (PPI) - 12how do you calculate image sizewidth x height
- 13what is DPIDots Per Inch or known as pixel density
- 14What is DPI and PPI used forits used to work out the quality of a image
- 15what is PPIused onimages ob a computer screen
- 16what is DPI used forprinted images
- 17what is colour depthcolour depth is the amount of bits used to indicate a colour on a single pixel for a bitmap image
- 18what does 1 and 0 mean in colour depth1 = white
0 = balck - 194 bit colour depth, how many colours can you get16 different colours
- 208 bit colour depth, how many colours can you get256 different colours
- 21what is the bit depth for true colour24 colour bit depth
- 22how do you calculate a file size(width x height) x colour depth
- 23two factors that can alter image file sizeMetadata
and
compression - 24what is compressioncompression is a method used to reduce file size.
any type of data can be compressed - 25what are the two types of compressionlossless
and
lossy - 26what is lossy compressionwhen it permanently reduces the file size.
the image is reconstructed without the deleted data
smaller file size means a loss of quality - 27what is lossless compressionwhen the file is temporarily reduced.
it regains its lost data when the file is opened
this does not reduce the quality and no data is not lost - 28what are the two types of lossless compressionRLE (run length encoding)
and
ZIP files - 29what is soundsound is vibrating waves
- 30two types of soundanalogue
and
digital - 31what is analogue soundanalogue sound that are waves that are pure and perfect quality
- 32what is digital soundis any computer recorded sound that isn't pure
- 33what is a sample or samplingSampling is simply
recording snapshots
(or snippets) of sound at set
intervals. - 34what is sample ratethe number of times the sound is sampled per second measured in Hz
- 35what is bit depthnumber of bits used to store each sample.
measured in Kbits/s - 36two types of sound filesWAV and MP3
- 37What is MP3 filesMP3 files are a form of lossy compression
- 38what are WAV filesthese are the native windows format that are bigger then a MP3 file. WAV files are lossless
- 39what effects the quality of soundsample rate
bit rate
bit depth
Quantisation - 40what is encryptionthis process of encoding data into a unreadable form
- 41what is dycryptionthe reverse of encryption where you break the code to make the data readable
- 42what is symmetric encryptionwhere the sender and the reciver share the encryption key to encrypt or decrypt the messege
- 43what is caesar chipherits a form of enycryption where you shift the letters to make the data undreadable
- 44benefits of encryptioneasy to use
protects valuable information
legal requirment when handling with personal data - 45diadvantages of encryptionforget the key
easy to solve if the encryption is weak
can be expensive and takes a long time to learn encrytion teachniques - 46what is a databasewhere you can store and retrive data
- 47what is a structured databaseArranged in an organised, precise and defined way
(using rows and columns in a database). - 48what is unhstructured dataData which is not organised in rows and columns.
- 49two types of databasespaper database
computer database - 50two types of computer databasesflat file
relational - 51what is a flat file databasea database where all of your
data is stored in one big table. - 52disadvantages of a flat file databaseduplicated data
takes up more storage
containing errors
takes longer to find data - 53what is relational databasesRelational databases split data across different tables to reduce
duplication (rather than having all of the data in 1 table). - 54what is fieldone piece of information
- 55what is a recordall the data about one item
- 56what t=are the 3 keys in a databaseprimary key
foregin key
Composite Primary Key - 57what is a primary keya unique way to identify each record on the database
- 58what is a foregin keyA field in one table that is a primary key in
another table. - 59composite primary keyMore than ONE primary key is used
to uniquely identify a record. - 60what are the 3 types of relationshipsone to one
one to many
many to many - 61what is one to one relationshipEach record in one database table is linked to 1 and only 1 other record in another table.
- 62what is one to many relationshipsEach record in ONE table can be related to many rows
in another table. This is the most common type of database used. - 63what is many to many relationshipsOne or more records in a table can be related to 1 or many records in another table.
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- Computer Science FlashCards sobre computer science , criado por Fakhri Samer em 20-02-2017.
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- Fakhri Samer
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