6. The Harvard Architecture

To overcome the problems discussed on the previous page, the idea is to split memory into two parts - one for data and the other for instructions.

This is the Harvard Architecture.

Each part is accessed with a different bus. This means the CPU can be fetching both data and instructions at the same time. There is also less chance of program corruption.

Also memory caches can be optimised for both instructions and data.

The problem with the Harvard architecture is complexity and cost.

Instead of one data bus there are now two. Which means more pins on the CPU, a more complex motherboard and doubling up on RAM chips as well as more complex cache design. This is why it is rarely used outside the CPU.

But this architecture is sometimes used within the CPU to handle its caches.