11. Mouse and keyboard sockets These are round, and often colour coded to show which is the mouse and which the keyboard. (The connectors might have little pictures of a mouse and keyboard on as well.) Very old computers will have a large round socket for the keyboard (called an AT socket) while older computers use the smaller sockets called PS/2 sockets. Many modern computers have only USB connections, so it is important to make sure that you buy the right mouse and keyboard for your computer or you will also need to get a converter.