The instructions used by Atmel 89CXX and 89CXXXX are the same or subset of 8051 microcontrollers. Some of the attractions in going for these microcontrollers include: Fully static operation, flash...
8051 is generic name. at89c51 is a variant of 8051 manufactured by atmel. it has a flash memory while older 8051 has no memory (runs from external eeprom)
8051 and 89c51 are same architecture but difference is ROM memory .ROM less for 8051 while ROM (flash) for 89c51.it advanced EEPROM (flash) is difference.
The Intel 8051 is a single chip microcontroller developed in the 1980s. It has now been largely replaced by its descendants with the Intel designation of MCS51 for the 8051 family.The PIC is a family...