111292
Description
Mind Map by scott.dowle, updated more than 1 year ago
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Created by scott.dowle
over 11 years ago
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Error Detection
- Used to check data has been
read correctly or transmitted
correctly
- Parity Bits
- Odd Parity
- Parity bit set so there are
an odd number of 1's
- For 11011010 parity would be 0 as
there are five 1's in the number
already making the number be stored
as 11011010
- Parity bit set so there are
an odd number of 1's
- Even Parity
- Works in same way except
parity bit is set so the number
of 1's is even
- Special case of a Cyclic Redundancy Check (CRC)
- Works in same way except
parity bit is set so the number
of 1's is even
- Quick way of
detecting errors but
isn't very thorough as
if 2 bits have
changed rather than
1 it wont be noticed
- Odd Parity
- Checksums
- Calculated by adding
together all the 1's in a
transmitted packet of
data.
- Total then transmitted as
a separate byte and
process repeated at
receiving end to
determine if error has
occurred
- Calculated by adding
together all the 1's in a
transmitted packet of
data.
- Echo Checking
- Primitive method of data checking
- Receiving computer transmits
data back to original computer
so it can be compared to
original
- Errors doubly likely as error may occur
in the data being transmitted back
- Primitive method of data checking
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