[Coco] CoCo OS-9 CRC32, Was: Ambiguous code

Chuck Youse cyouse at serialtechnologies.com
Thu Sep 25 21:46:48 EDT 2008


On Thu, 2008-09-25 at 18:36 -0700, Stephen H. Fischer wrote:
> I was addressing the point that the checksum calculation was unsafe for many
> uses. Use of checksums anywhere bothers me.
> 
> But possibly it is adequate for its intended use here.
> 
> Should it not be, that the CoCo (OS-9 at least In my experience), can check
> the validity Of files transferred from other Computers and that the source
> code for the CRC32 calculation is available for OS-9.

Ah.  As you are probably aware, there's a "calculate 24-bit CRC" system
call in OS-9. :)  I suspect Boisy's choice here was one of performance;
having the Coco compute a CRC-16 on every 256-byte block is 'spensive.
With XMODEM-CRC at 300 baud, who cares, but when you're pretending
you're a disk .... 

C.





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