On Tue, 6 May 2003, William Chops Westfield wrote:

> >> Can anyone tell me how the X-Modem crc is calculated for the packet.
>
> Xmodem is a simple 8-bit checksum.
>
> Ymodem uses (x^16+x^12+x^5+1)
>
> Did you look at the document I mentioned last week?
>
> http://www.geocities.com/westfw/ymodem.txt

And if he's lucky, the CRC has already been implemented:

http://www.dattalo.com/technical/software/pic/crc.php

Scott

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