"The '251 also has a "source" mode which changes the instruction set to include 16 and 32 bit instructions while retaining 8051 std instructions. The machine includes an improved register file as well."
Yes, I know but
all addressing 2 component (a C speedo)?
How many software interrupts?
How many interrupt priorities?
Separate Rx and Tx interrupt?
16/8 bit bus selectable?
port configurability ?
derivative with actual address lines (not p0,p2)?
64k flash IAP derivative?


"1k of sram include on chip. The address space was increased to a logical 1 MB (256 practical) with a page mode to speed external memory access."
different, but the same except 16Mb address.

Erik