On Fri 12-Feb-2021  7:27a, Pzembrod@gmail.com@3:770/3.0 wrote:
P> I figure that someone here probably knows why CBM's basic RAM always
P> started at $xx01 addresses, like $0801, $0401, $1001, $1c01 instead of
P> $0800, $0400, $1000, $1c00?

P> What is sitting in that one byte, or what role is it playing?

I am not sure about the other systems, but on the C64 the Byte at $800 indicates your intention to use the following bank for Basic.  If you store anything other that 0 in that Byte, then Basic programs will not run.

[+] K-Guide
--- CNet/5