Advanced PC Architecture

The internal architecture of the PC is changing for many reasons, including:

Author: Dr W.Buchanan, Napier University, Edinburgh. Downloads: None yet		Phasing-out of old legacy busses and devices. PCs have, in the past, been difficult to configure and to add new equipment to, as they are still very much based on legacy sys-tems. The worst offender of this is the ISA bus which requires the use of interrupt lines (IRQs) and special memory address (I/O ports). These have always been difficult to con-figure and normally require some degree of expertise before they can be correctly configured. New interfaces, such as the USB, allow for the automatic identification and configuration of a device and for addition and deletion of a device while the PC is still powered on.
		Increase in the system data rate. Over the years, the processor has increased its speed, but the system board has struggled to keep up with these increases. New architectures are now being developed which more closely match system memory and the graphics controller to the processor, while moving other devices and interfaces, such as the hard disk and communication ports, away from the processor. This allows high-speed devices to have direct access to the processor, allowing for increased data transfer to and from memory, and for enhanced 3D photorealisitic graphics.
		New memory devices. Traditional memory (DRAM) can be slow when compared with the processor speed. New memory devices, such as RDRAM, have now been developed which allows ultra-high data transfers between the processor and the memory.
		New plug-and-play architectures. USB provides a great deal of enhancements over traditional connections, and will be used extensively over the next few years to connect devices to the PC.
		Increased usage of electronic bridges. These segment the PCs into segments which are more closely matched to the speed of the device. A typical device is the PCI bridge.

This book provides a foundation on the understanding of previous, current and future PC systems. These principles will allow undergraduates and professionals to fully understand how the specification of each component of a PC affects overall system performance.

It outlines each of the main PC processors and contrasts their performance. It also exam-ines each of the main interface devices and shows how they integrate into the complete system. In the motherboard material, previous, current and future motherboards are shown in some detail to allow undergraduates and professionals to understand how data is passed around the PC. The main objectives are to:

	Provide a complete understand of all PC systems, current or future. This helps in under-standing the specifications of a computer so that users can purchase the required specification for their application.
	Provide an insight in how PC systems will involve in the future. This will allow hard-ware and software developers to properly understand how they design and develop their products to encapsulate new systems
	Show how systems have evolved from the original PC to current and future systems. This shows how the PC has kept compatibility with previous systems, but increased its power.

One of the main aims of this book is to provide a foundation on the understanding of previ-ous, current and future PC systems, and how the specification of each component of a PC affects the overall system performance. It shows where PCs have been in the past, where they are now, and how new architectures and interfaces devices will change the PC from a difficult-to-use, difficult-to-configure and difficult to add-to system into an easy-to-use su-percomputer.

With new GHz processor speeds, and new memory and interfacing techniques, the PC is never going to be the same again. For the first time, the PC will discard the past and look towards the future. First in line in the discard pile will be the ISA bus, and gone forever will be IRQs and complex software set-ups. In will come true plug-and-play and hot addi-tion/deletion.

The PC is dead. Long live, the PC. For 20 years the PC has struggled along with the same old system, and trying to be compatible with its famous father: the IBM PC. From now on, the PC will change, and things will never be the same again. In order to take it into the su-percomputer range it must change. Thus everything is changing: its architecture, its memory, its graphics, its sound, in fact, almost everything. In will come a new shining system which will be one of the greatest achievements, ever!

So which chapters should you read if you really want to get a good understanding of the PC. Well we would recommend:

	Motherboards (Chapter 27) and Hub-based architecture (Chapter 28). These chapters analyse typical motherboards and chipsets and show how each of the components interfaces together, and how the architecture affects the system performance.
	Memory (Chapter 12). This chapter shows how cache memory and DRAM memory interfaces to the system, and the processor. It also outlines how SDRAM and RDRAM enhance the data transfer rate over traditional memory types, such as EDO RAM.
	PCI bus (Chapter 18) and AGP bus (Chapter 24). This chapter discusses the funda-mentals of the PCI bus and shows its importance in the architecture of modern PCs. This concept is then further enhanced in the AGP chapter, which has used the PCI bus as a foundation and then enhanced it to provide for high-speed graphics transfers.

As much as possible little interesting inserts have been added to the text. Maybe they should provide a light relief to the more academic material.