I have no idea why this BRK was put there in the first place. At least nowadays it's pretty common to see IP packets that IP65 doesn't understand / need to understand. Just think of IGMP packets. We certainly don't want to crash on receiving those!
It's the very purpose of the DATA segment to consolidate all items that potentially need to be copied from ROM to RAM. So there's no need to / point in doing that on a per-item-base.
- Tab chars were partially used with the unusual width of two blanks. I removed them altogether.
- Line endings were inconsistent even iniside individual files. I normalized them.
- I introduced a consistent coding style regarding comment indenting and blank line usage.
- I removed trailing spaces.
- I removed newlines following unnamed labels.
- ...
- Simplify Makefile by allowing to use suffix '_tcp' to denote the requirement to link against TCP-capable IP65 lib.
- Remove 'test' or 'test_' prefix from test program names - every program in 'test' is a test program.
- Have some more test programs switch to lower case charset on the C64.
- I'm no Ruby guy so don't rely on Ruby for building disk images.