Xbox Hardware Overview

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The Xbox is a standard PC, based on standard components, but extended with a some security solutions. This document gives an overview of the components the Xbox is made of.

Overview

Viewed by connection (similar to the Windows 2000 Device Manager view), the Xbox system hardware looks like this:

Diagram modified by Fahad

Xbox V1.0-1.5
|
|-- Mobile Intel Pentium III 733mHz w/128kb Cache
|
|-- Flash ROM (V1.0/1.1 -
|
\-- PCI bus
    |
    |-- Programmable Interrupt Controller
    |
    |-- System Timer
    |
    |-- DMA Controller
    |
    |-- PCI Bridge Device - Host Bridge									(0:0:0, 0x2a5)
    |
    |-- Memory Controller - SDRAM - Samsung K4D263238M-QC50 133mHz 16mb			(0:0:3, 0x2a6)
    |   |
    |   |-- Top of Motherboard 
    |   |   |
    |   |   |-- Pad 1 (closest to power connector) (empty)
    |   |   |
    |   |   |-- Pad 2 (left of Pad 1)
    |   |   |
    |   |   |-- Pad 3 (below Pad 4)
    |   |   |
    |   |   \-- Pad 4 (closest to AV connector) (empty)
    |   |
    |   \-- Bottom of Motherboard
    |       |
    |       |-- Pad 5 (paralell to Pad 1) (empty)
    |       |
    |       |-- Pad 6 (paralell to Pad 2)
    |       |
    |       |-- Pad 7 (paralell to Pad 3)
    |       |
    |       \-- Pad 8 (paralell to Pad 4) (empty)
    |
    |-- HUB Interface - ISA Bridge 									(0:1:0, 0x1b2) [nForce]
    |
    |-- SMBus Controller	 										(0:1:1, 0x1b4) [nForce]
    |   |
    |   |-- PIC16LC
    |   |
    |   |-- Conexant 25871/Focus 454/Xcalibur Video Encoder
    |   |
    |   |-- ADM1032 System Temperature Monitor
    |   |
    |   \-- Serial EEPROM
    |
    |-- OHCI USB Controller 											(0:2:0, 0x1c2) [nForce]
    |   |
    |   \-- USB HUB (Controller Ports 1 & 2) 
    |
    |-- OHCI USB Controller 											(0:3:0, 0x1c2) [nForce]
    |   |
    |   \-- USB HUB (Controller Ports 3 & 4)
    |
    |-- MCP-X V3 Southbridge 
    |   |
    |   |-- MCP Networking Adapter 									(0:4:0, 0x1c3) [nForce]
    |   |
    |   \-- MCP APU 												(0:5:0, 0x1b0) [nForce]
    |
    |-- AC`97 Audio Codec Interface 									(0:6:0, 0x1b1) [nForce]
    |
    |-- Simple Communication Controller - Generic Modem 	(0:6:1, 0x1c1) [???]
    |
    |-- IDE Controller 											(0:9:0, 0x1bc) [nForce]
    |   |
    |   |-- Primary IDE Channel
    |   |   |
    |   |   |-- Seagate ST3210014ACE 10.2gb (8gb used)/Custom Western Digital WD80EB 8gb hard drive
    |   |   |
    |   |   \-- Custom Samsung/Phillips/Thompson/LG DVD Drive
    |   |
    |   \--- Secondary IDE Channel
    |
    |-- PCI Bridge												(0:8:0, 0x1b8) [nForce]
    |
    \-- AGP Host to PCI Bridge										(0:30:0, 0x1b7) [nForce]
        |
        \-- NV2A GeForce 3MX Integrated GPU/Northbridge 233mHz					(1:0:0, 0x2a0)

PCI devices have their Bus:Dev:Func numbers as well as the DevID printed next to them. PCI devices with "[nForce]" have the same DevIDs as their counterparts of the nForce chipset.

A derivative of the Xbox chipset is also available as the PC chipset "nVidia nForce", which consists of a northbridge with the memory interface and the GPU and the southbridge with the PCI bus and its devices, just like the Xbox chipset. Many of the southbridge PCI devices are the same on both versions, i.e. they have the same DevID.

The Devices in Detail

Intel Pentium III CPU

The CPU is a standard Pentium III Coppermine mobile at 733 MHz. This CPU has been found to be a modified Pentium III, as it has many of the features a Celeron lacks. Therefore, it can be classified as a Pentium III with a smaller cache. (Regular has 256kb or more, XBox has 128kb)

Flash ROM

See Flash ROM

PCI bus, Host Bridge, ISA Bridge, AGP Host to PCI Bridge, Memory Controller

These devices are identical to the corresponding devices contained in the nForce chipset. The PCI bus can be accessed like on any PC.

Programmable Interrupt Controller, System Timer, DMA Controller

These legacy PC/AT system devices are fully PC-compatible, but the timer frequency is 6% higher than in a PC.

SMBus Controller

Some low-speed devices are connected through the SMBus, so the southbridge contains an SMBus controller, compatible to the SMBus controller in the nVidia nForce chipset. Since nForce is based on AMD's original chipset for Athlon CPUs, the SMBus controller is AMD-756 compatible.

PIC16LC

See System Management Controller

Video Encoder

See Video Encoder

ADM1032 System Temperature Monitor

The Analog Devices ADM1032 is an SMBus device that does temperature measurement.

Serial EEPROM

See EEPROM

OHCI USB Controller, IDE Controller

These devices are compatible to standard PC devices.

MCP Networking Adapter, MCP APU, Audio Codec Interface

These are identical with the nForce devices.

Simple Communication Controller - Generic Modem

Nothing is known about the purpose of this device. It never gets used by the Xbox system software. It is probably there, because the nForce has a PCI softmodem, but in the Xbox, the corresponding lines of the Southbridge don't seem to be connected.

NV2A GeForce3 Integrated GPU

The Xbox graphics hardware is VGA compatible and very similar to existing nVidia graphics cards.

Further Information

Information about all chips and links to technical documentation can be found at Pixel8's site somehting