[Coco] Fwd: IP packets on my coco

Dave Philipsen dave at davebiz.com
Wed Jun 8 01:27:51 EDT 2016

I remember from the CRC calculation in X/Ymodem that there is an easy 
and faster way to get the CRC using lookup tables.  That's how I did it 
with Supercomm.  I believe the CRC for the networking packets is a 
32-bit CRC so I don't know if lookup tables are still practical or not 
with that size CRC.  What is amazing is that I was able to find that 
information without the internet back then.  I just now did a few 
cursory searches on calculating CRCs and I'm guessing that there is a 
fairly easy method that doesn't require so much overhead.


On 6/7/2016 10:39 PM, Brett Gordon wrote:
> Nice!  I found that the fun part about CRC specs... they are usually
> imcomplete.  They might tell you a polynomial.  but they seem to forget to
> tell you all the minutiae.
> Brett M Gordon
> On Jun 7, 2016 10:12 PM, "Barry Nelson" <barry.nelson at amobiledevice.com>
> wrote:
>> I don't know about getting the chip to compute the CRCs, but I have some
>> old 6809 assembly code I developed to computer CRCs for Xmodem CRC. It's in
>> the XCOM9 source code. I don't know how useful it will be.
>>> Brett Gordon beretta42 at gmail.com
>>> Tue Jun 7 18:56:07 EDT 2016
>>> Hah...answered my own question..these chips take layer 2 ethernet
>> frames...
>>> not too horrible to program for but....computing the CRC in the coco is
>>> slow and painfull.  Does one of these chips do the for us?
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> https://pairlist5.pair.net/mailman/listinfo/coco

More information about the Coco mailing list