Main memory is located on the CPU chip?

Answer 1

The only memory located on a computers CPU chip is called the cache.... typically about 1-8MB in size it acts as a rapid access 'buffer' for immediate actions.

The main memory is usually termed the RAM and sit's nexto the CentralProcessorUnit - connected by the FrontSideBus (board circuitry), size.... well depending on age anything from a few MB to 16GB (dependant on a number of factors).

Actually, the term "main memory" is reserved for the primary location where active work is stored. In modern computers, "main memory" consists of DRAM chips mounted somewhere near the CPU. Thus, "main memory" is never on chip. The reason for this is cost - providing memory inside the CPU is hideously expensive, there is a limit to how much can be put there, and the amount can never change. Off-chip main memory allows very significant cost savings, and allows the amount of memory to be adjusted freely.

There are generally TWO types of memory that are located on-chip, however. Cache memory (which can come in various "levels", describing how far away from the main CPU each memory bank is) is used to keep copies of data from the main memory in a location that is "closer" to the CPU, and thus faster to access and use. Registers are memory located directly inside the CPU's execution units - think of them as scratch space where the CPU can temporarily store small amounts of data while it does a calculation. For instance, if a CPU is asked to do: A+B=C, it will have to load A into a register, then load B into a register, then do the calculation, saving the result into a register, then finally load the "results" register value back into C.