Found the summary I was doing.
You can see I was toying with a new board type:
the existing 328 types with 20 IO
the existing 1284 types with 32 IO
a new 1281 type with 54 IO, "milliduino"
the existing 250 types with 86 IO
I should make one up & try it ...
chip comparison.xls (56 KB)