Data transmission Flashcards
Bit
Short for binary digit, it is the smallest unit of data in a computer.
Bit rate
The rate at which data is transferred.
How the data are transmitted?
The transfer of data occurs either wirelessly by radio waves or over a cable.
Serial transmission
Use a single wire to transfer bits of data.
Parallel transmission
Uses a multiple wires to transfer bits o data
Interference
Disturbances that can occur in the signals when sending data that may corrupt it.
Serial transmission properties
- used over long distances
- used a single wire
- reduced costs
- slower transmission as only one bit at a time
- safer transmission as one bit is send at a time
Parallel transmission properties
- used over a short distances
- uses multiple of wires
- increased cost
- quicker transmission
- less safe as bits are send in parallel
Simplex transmission
Sending data in one direction only at time.
Full duplex transmission
Sending data in both direction at the same time.
Half-duplex transmission
Sending data in both directions but only one direction at time.
Checksum
Method of error detection. The number of bits is counted up and the receiver can check, if same number of bits it received.
Parity check
Method for error detection. The devices that the data is being transferred between will be set to check for even parity or odd parity before the data is sent.
Automatic repeat request
Is a set of rules for error control when transmitting data. When the device detects that there is an error, it will automatically sends a request to resent the packet.
USB
Universal serial bus. Transmits data much faster than parallel transmission. It is more expensive than parallel.
IC
Integrated circuit. It uses parallel transmission. It is cheap, simple and fast. Used mainly in microprocessors.
HTML
Hypertext markup language. Consists of the content to be displayed and instructions on how to interpret the content.
Mark-ups
Instructions on how content is formatted, structured and displayed by the browser.
By separating the style form the content…
the style can be easily changed without changing the content.
CSS
Cascading style sheet, which specifies the presentation. Separated document where styling mark-up instructions are placed. This sheet can be then applied to any HTML document.
