Central processing unit in computer architecture pdf CPU sends signals to control the other parts of the computer, almost like how a brain controls a body. 8-bit or 16-bit word size. When CPUs were invented in the middle 20th century they had many different word sizes.

Some had different word sizes for instructions and data. The less popular word sizes later stopped being used. Some chips with microprocessors inside them also contain other components, and are complete single-chip “computers”. A CPU usually has many registers. Therefore, they are part of the CPU chip itself. Therefore, registers usually only store the data that the CPU is working on “right now”.

RAM is usually stored outside the CPU in separate chips. The size of addresses is often the same as the word size: A 32-bit CPU uses 32-bit addresses, etc. However, smaller CPUs, like 8-bit CPUs, often use addresses that are larger than the word size. Otherwise the maximum program length would be too short. Because the size of addresses is limited, the maximum amount of memory is also limited. 32-bit processors can usually only handle up to 4 GB of RAM.