The heart of the modern electronic system is the microprocessor e.g. the video, sound, game consoles, portable phones and domestic appliances. Let us consider the heart of a home computer. The home computer consists of many peripheral devices, such as Disk drives, DVD drives, power supplies specialized PC cards for graphics, movies, sound etc. These devices centre about the motherboard, the heart of the system. This provides the interconnection for the disk drives, power supplies, the peripheral cards and links them to four key devices: namely the microprocessor, the system RAM, the IO controller and finally the Basic Input Output system (BIOS) EPROM as seen below 

Within other modules you have used high level programs to generate movies, sound, and control of other devices. In order to fully understand the working of modern microprocessor products we must take a closer look at the operation of these devices and program using binary and assembly language to understand the role of the EPROM on the motherboard. The microprocessor which we have chosen to look at in more details is the Motorola MC68HC11, one of the current 8 bit CPU's. Even though this is a micro-controller, it helps to introduce you to the complex working of the Pentium and Pentium II on a PC and yet enables you to easy understand the 8 bit micro-controllers used on many home products.