What are the functions of the different units in the CPU?

Answer 1

The CPU (central processing unit) chip today includes one or more ALUs, one or more AGUs, and one or more FPUs. The ALU is the Arithmetic and Logic Unit, and that is used for common tasks. It might also be known as the Execution Unit. The AGU is the Address Generation Unit, and it is used for addressing memory. The FPU is the floating point unit, and that is for working with complex numbers. Modern CPUs also include a memory controller.

Then there is the GPU, or Graphics Processing Unit. That is what renders the graphics and outputs a display. It also addresses the video memory and also performs graphics-related tasks so the CPU doesn't have to, thus speeding up graphics.

There is the Northbridge chip. That is part of the chipset and includes tasks such as being the memory controller, providing a graphics bus (AGP controller on somewhat older PCs), and providing a bus for the Southbridge which controls the rest of the computer past that point. Most of these functions are now integrated into the CPU.

There is also a Southbridge chip. It is the circuitry which ties to the peripheral devices, the peripheral bus, the USB controller, the hard drive controller, the floppy controller (if the system has one), integrated sound, the mouse, the keyboard, and the ROM BIOS.

There is the memory, it is what holds the operating system and programs while they are in use.

There are the storage devices. The hard drive is the most common device in this class, and there are also CD/DVD devices.

There are input devices. These are your mouse, keyboard, any tablets you might have, or similar.

There are output devices. These would include the video card, the monitor, and any printers and plotters.

There are networking devices. These include network and WI-FI cards and are used to connect your PC with other PCs.

There is the ROM BIOS which is a chip containing the code used to bring up the PC. That is what initializes the computer, brings up the CPU, provides basic functionality for devices, and loads the operating system. Once the OS is loaded, it takes over most of the functions that the BIOS provides.

Answer 2

control unit(CU) and arithmetic logic unit(ALU)