Hi Will, actually as far as I know AutoCAD has not been limited to 256 layers for quite a long time.

It looks like with R14 and higher there is no limit, and for R13 and prior (not sure how far back) it was limited to 32767 layers (which is a 15 bit limit, sometimes the high bit is reserved for a negative/positive sign bit).

So I think this is one of those rare areas that you can't really blame on AutoCAD...

Some programs that have been around for a while probably have this limit more to maintain compatibility with their own older versions of the same program.

- Michael