I see no discernible difference between the DS89C420 and DS89C430. Why different part numbers? The instruction set timing appears equal and all SFR's appear the same.

Dallas specs say that the DS89C440 and DS89C450 are no different with the exception of 32K and 64K program memory with different and proper default values for their ROMSIZE SFR.

Therefore, with the exception of program memory size and ROMSIZE SFR, are these 4 microcontrollers the same?

Thanks,

Dan