Data Transmission and Data representation Flashcards
Serial Transmission
Uses a single wire to tranfer the data bits
Parallel data transmission
Uses severaral wires to transfer data bits simultaneosly
Which transmission is more expensive? Why?
Parallel data transmission. Uses multiple wires
Which transmission is used over long distances?
Serial transmission
Which transmission is quicker?
Parallel transmission
Which transmission has more errors? Why?
Parallel as bits are sent simultaneosly ans errors can occur
Simplex transmission
Sending data in one direction only
Duplex transmission
Sending data in both directions at the same time
Half-Duplex transmission
sending data in both directions, but only one at a time
Checksum
Certain calculation happen to the bits and then the check digit is send. The reciever does the same operations and compares them to the check digit
Parity check
The last bit is used for the check. The sum of all bits should be even
Check digits
A calculation is performed and the check digit is added to the end of the code. The computer will perform the same calculations and compare to the check digits
Automatic repeat request
If the reciever detects the data it asks to resend the package. Untill the package is error free, or a limit has been reached.
Register
A small piece of memory where values can be held
Character
text, numbers and symbols, for example each key on a keyboard
Algorithm
a step-by-step set of instructions
How does compression work?
Making a file smaller using compression algorithms
List 2 types of compression
1) Lossy compression
2) Lossless compression
Lossy compression
Data, which is unnecessary is completely and permanently removed
Lossless compression
No loss, compression can be reversed and reconstructed, the file will be exactly as it was
Where can lossy compression be used? (3)
1) Images
2) Audio
3) Video
Where can lossless compression be used (3)
1) Music
2) ZIP
3) Text
What does lossy compression remove?
Background noises - not useful, but takes space
What does lossless compression remove?
Repeated patterns from a file. It would store the pattern once and where and how many times it is repeated
List two ways of storing text
1) .doc
2) .pdf
List two ways of storing data
1) .csv
2) .xls
List two ways of storing audio
1) .mp3
2) .mid
List two ways of storing video
1) .mp4
2) .flv
List two ways of storing images
1) .jpg
2) .gif
Binary
A system of numbers with a base of 2. Each unit used increases by the power of 2
Debug
Finding and fixing problems and errors in a program
Bit
Short for binary digit, it is the smallest unit of data in a computer
Interference
Disturbances that can occur in the signals when sending data that may corrupt it
Where is checksum used?
To detect human errors in ISBN’s, barcodes
