In a normal computer that follows von Neumann architecture, instructions and data both are stored in same memory. So same buses are used to fetch instructions and data. This means CPU cannot do both things together (read a instruction and read/write data).Harward Architecture is the computer architecture that contains separate storage and separate buses (signal path) for instruction and data. It was basically developed to overcome the bottleneck of Von Neumann Architecture. The main advantage of having separate buses for instruction and data is that CPU can access instructions and read/write data at the same time.