can only guess at the original plans at Cygnal wherein the first chips may have been intended to have full cross point switch. However the chip designers probably said "You want a 64x64 cross point matrix" ??## Forget it.

I heard at at Cygnal (yes Cygnal, it's a while ago) that originally a matrix was considered but it was shown to occupy 80% of the die and that led to the crossbar.

When a design is not completely defined at design start (I hate those) I typically enable one I/O of a group which then later can be reconfigured to another I/O within that group. As an example, I currently have a design that does not use timer in/out or external interrupt, I have enabled a timer out which then, should the need arise, can be configured as an interrupt or a timer in or a timer out. That actually is an advantage of the crossbar, you can leave ONE pin open and have 3 options for using it, in a 'standard' '51 you would have to leave 2 port 3 pins open to have the same options.

Is the crossbar the right solution, I do not think so, but in addition to it6s disadvantages it does have advantages.

Erik