Hacking the Xbox

CHAPTER 10
More Hardware
Projects
The similarity of the Xbox to the PC architecture allows hackers to borrow
technology and expertise from the PC world when building hardware
projects. As a result, PC hardware, monitors, cables, and peripherals have all
been adapted to work with the Xbox. This chapter introduces some of
these hardware projects, discovered, documented and implemented by
hackers around the world.
The LPC Interface
Version 1.0 of the LPC (Low Pin Count) interface was defined by Intel in
1997. The LPC interface is a royalty-free bus that is designed to enable
systems without explicit ISA or X-bus (ISA-like expansion bus for memory
or generic I/O devices) capabilities. The need for the LPC interface stems
from the large number of low bit-rate, high pin count devices and busses
with incompatible interfaces found in a standard PC, such as the floppy
disk, keyboard, mouse, serial, IrDA, parallel, ISA, and boot ROM interfaces.
The aggregate bandwidth consumed by all these devices is small, but the
number of signals required to support all of them easily exceeds the signal
count required by higher-bandwidth buses such as the PCI or AGP bus.
Making matters worse, not all configurations of computers requires all of
these legacy I/O devices, and wasted pins and functions just eat away at
profits. The cost of a pin on a chip package is high relative to the cost of the
silicon required to support these simple interfaces. (A rule of thumb is that
one package pin costs a penny, while in 0.13µ silicon, about ten thousand
gates — enough logic to implement a small processor—costs a penny in
silicon area, assuming the design is not bond-pad limited 1 .)
The LPC interface counters this problem with a single, low-pin count (seven
required pins, versus the 36 pins required for an ISA bus) bus that operates