Communication and internet technologies
- Created by: Alexia
- Created on: 11-12-18 09:55
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- Communication
- Data transmission
- Simplex
- 1 direction only
- Half-duplex
- 2 directions but NOT at the same time
- Full-duplex
- 2 directions at the same time
- Serial
- data is sent one bit at a time over a single wire
- Parallel
- several bits of data are sent down several wires at the same time
- Universal Serial Bus (USB)
- Asynchronous
- data being transmitted is in a pattern - start and stop bit
- Synchronous
- continuous stream of data - timing signals generated by an internal clock
- Simplex
- Error Checking
- Parity Checks
- even or odd (number of bits) - PARITY BITS
- The blocks identify an erroneous (corrupted) bit
- Cannot identify all errors
- If the byte hasn't changed but there still is an error
- Checksum
- The checksum is sent at the end of the block
- Based on the number of bytes in the block
- Data is sent in blocks
- An error in transmission if the check sums don't match at both ends
- Echo check
- Data is returned to the sender
- Who compares the data sent with the data received
- If the data is different - transmission error
- Data is returned to the sender
- Automatic Repeat Request (ARQ)
- Uses an acknowledgement to indicate data received correctly
- A timeout is used - time allowed to elapse before an acknowledgement is received
- Parity Checks
- Internet Technologies
- Internet Service Provider
- Provides the user with access to the internet - feeed
- Internet Protocol (IP) address
- Untitled
- Media Access Control address (MAC)
- uniquely identifies a device connected to the internet
- HTML
- Structure: part of HTML documents: includes semantics and structural mark-up of documents
- Presentation: style of the document
- Hypertext Transfer Protocol (http)
- rules that must be obeyed when transferring files across the internet
- Internet Service Provider
- Data transmission
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