Images For Important Parts Of Computer. Everything inside the computer is connected to a circuit board called the 'motherboard'. The motherboard has sockets for low-level programming (BIOS), the computer's brain, called a CPU; the computer's memory (RAM, ROM and CMOS); and for add-on cards to control the video (picture), audio (sound), printer and anything else that might be connected to the computer. You may also find a modem inside on an add-on card.