Which of the following has a Harvard architecture?

The correct answer is D. CSIRAC.

A Harvard architecture is a computer architecture where instructions and data are stored in separate memories. This is in contrast to a von Neumann architecture, where instructions and data are stored in the same memory.

EDSAC, SSEM, and PIC all have a von Neumann architecture. CSIRAC, on the other hand, has a Harvard architecture.

CSIRAC was an early computer developed in Australia in the 1940s. It was one of the first computers to use a transistor, and it was also one of the first computers to use a Harvard architecture.

The Harvard architecture has several advantages over the von Neumann architecture. One advantage is that it can improve performance by allowing instructions and data to be accessed in parallel. Another advantage is that it can improve security by preventing instructions from being accidentally or deliberately modified.

However, the Harvard architecture also has some disadvantages. One disadvantage is that it can be more complex to design and implement than a von Neumann architecture. Another disadvantage is that it can be more difficult to debug programs that are written for a Harvard architecture.

Overall, the Harvard architecture is a powerful and versatile architecture that has been used in a variety of applications. It is particularly well-suited for applications where performance or security are critical.