[TUHS] why is sum reporting different checksum's between v6 and v7

[Clem cole]

A thought. Try recompiling v7 sum on v6.  It's simple enough that the compiler differences should be easy to tease out. 

Sent from my iPhone

> On Dec 11, 2015, at 7:03 PM, Will Senn <will.senn at gmail.com> wrote:
> 
> All,
> 
> While working on the latest episode of my saga about moving files between v6 and v7, I noticed that the sum utility from v6 reports a different checksum than it does using the sum utility from v7 for the same file. To confirm, I did the following on both systems:
> 
> # echo "Hello, World" > hi.txt
> # cat hi.txt
> Hello, World
> 
> Then on v6:
> # sum hi.txt
> 1106 1
> 
> But on v7:
> # sum hi.txt
> 37264     1
> 
> There is no man page for the utility on v6, and it's assembler. On v7, there's a manpage and it's C:
> man sum
> ...
> Sum calculates and prints a 16-bit checksum for the named
>     file, and also prints the number of blocks in the file.
> ...
> 
> A few questions:
> 1. I'll eventually be able to read assembly and learn what the v6 utility is doing the hard way, but does anyone know what's going on here?
> 2. Why is sum reporting different checksum's between v6 and v7?
> 3. Do you know of an alternative to check that the bytes were transferred exactly? I used od and then compared the text representation of the bytes  on the host using diff (other than differences in output between v6 and v7 related to duplicate lines, it worked ok but is clunky).
> 
> Thanks,
> 
> Will
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