I found some websites they say 8051 is von Numan architecture. But i studied in college , architecture of microcontrollers are Harvard.which one is correct?

 

From wikipedia:


Memory architecture
;
The 8051's instruction set is designed as a Harvard architecture with segregated memory (data and instructions); it can only execute code fetched from program memory, and has no instructions to write to program memory. However, the bus leaving the IC has a single address and data path, and strongly resembles a Von Neumann architecture bus.

 

But, externally there are two separate 64K address spaces. program data space is READ using PSEN* (Program Store Enable*), while the external data space is accessed using RD* and WR*.