In personal computers, the controllers are often single chips. When you purchase a computer, it comes with all the necessary controllers for standard components, such as the display screen, keyboard, and disk drives. If you attach additional devices, however, you may need to insert new controllers that come on expansion boards.
Keyboard Controller functions Describes the functions of the keyboard controller and what functions it provides. This page is from "The PC Guide".
System Chipset and Controllers Describes chipset functions and features, popular chipsets, controller and integrated motherboard functions. This page is from "The PC Guide".
Microcontroller primer/FAQ Contains general questions and answers about microcontrollers and embedded processors.