I need some data from secondary storage but I can only read from primary storage.
Data is then slowly moved into the buffer (RAM).
Once the RAM is full, an interrupt is sent to the CPU (control unit). This is tell the CPU that there is data waiting for it.
When the CPU becomes free the data is read to the cache in the CPU at speed.
I need to clear my cache by dumpping it in the RAM at high speed.
Data is then quickly moved into the buffer (RAM).
Once the RAM is full, it is moved into the secondary storage so that the CPU can continue using its cache.
When the RAM is finally empty, an interupt will be sent to the CPU so the it know it can be used.