Up to 65K of code memory and 65K of data memory can be added to any of the 8051 family members.

The 8051 is a 40-pin IC. Twenty-two pins are needed for the four I/O ports.

Writing counter/loop programs is much more difficult with the introduction of the DJNA and the CJNE instructions.

The ADC 0804 is an analog-to-digital converter that provides 8-bit output resolution that can be directly interfaced to a microcontroller.

Different instruction sets must make up for the various members of the 8051 family.