Checksum help! (1 Viewer)

[dimzi]

The problem im having with checksum is that I dont understand how they actually get the number at the end?

Say for this bit 01010011, what would be the checksum, and how do you get it?

I understand that if its over 255, then you have to 'divide' (which I think you actually have to subtract) 256 from the checksum.

Help?

 

[brownsound]

once u divide by 256 u get the remainder and that is the final number
u gotta add the bits together....so it mite b

27|18|107|3|74|0|63|
and the checksum will be 36
reason
27+18+107+3+74+0+63=292
292>255
hence
292/256=1 and 36 remainder
checksum =36

 

[Srixon]

IN checksum error detection, all the digitsin a flow of data are summed to amke a total. The total is transmitted at the end of the data block. the receiving computer adds the received data bits obtaining its own checksum if the checksum. If the checksums do not match there is and error. I am pretty sure that you do not divide nothing in checksum all it does is add up the digits and sees if it adds up to the same at the other computer. Cylic redundancy check is when u add up and divide it by a constant and then the remainder is attatched they recalculate it at the other computer to see if the remainder is the same. Hope that helps

 

[dimzi]

once u divide by 256 u get the remainder and that is the final number
u gotta add the bits together....so it mite b

27|18|107|3|74|0|63|
and the checksum will be 36
reason
27+18+107+3+74+0+63=292
292>255
hence
292/256=1 and 36 remainder
checksum =36

Thats what I didnt get (same textbook).

How could they get 27 or 18 or 107 etc in the data block?