On Fri, Mar 20, 2026 at 3:10 PM Brian White <[email protected]> wrote:
> No transmission errors, I just don't like for something to make a promise > that it doesn't actually do. > Good that you're keeping it honest. The Model T is from the age of innocence, before computers learned how to lie. > So now I have the simple xor as default for the speed, and the fact no one > is downloading these from bbs's over phone lines with modems that predate > mnp5 error correction any more, let alone manually typing them in. (look at > the original TINY loader, 40 column lines! The error message says "typo"!) > :-D > Probably the mod is the strongest, > I think you're right. I cannot claim to understand the math, but one of the things I did take away from Williams' classic text on Cyclic Redundancy Checks, *A PAINLESS GUIDE TO CRC ERROR DETECTION ALGORITHMS: Everything you wanted to know about CRC algorithms, but were afraid to ask for fear that errors in your understanding might be detected* <https://raw.githubusercontent.com/hackerb9/crc16-8080/refs/heads/main/adjunct/crc_v3.txt>, was that while summation makes for terrible checksums — certain bits are more likely to be flipped than others — division, particularly the remainder, is quite good. I believe a CRC is basically just long-division implemented via left shifts and exclusive ORs. —b9
