2000 National Semiconductor Corporation
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GeodeTM
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General Description
The National Semiconductor
GeodeTM GX1 processor
series is a line of integrated processors specifically
designed to power information appliances for entertain-
ment, education, and business. Serving the needs of con-
sumers and business professionals alike, it's the perfect
solution for IA (information appliance) applications such as
thin clients, interactive set-top boxes, and personal internet
access devices.
The Geode GX1 processor series is divided into three main
categories as defined by the core operating voltage. Avail-
able with core voltages of 2.0V, 1.8V, and 1.6V, it offers
extremely low typical power consumption (1.2W, 1.0W, and
0.8W, respectively) leading to longer battery life and
enabling small form-factor, fanless designs. Typical power
consumption is defined as an average, measured running
Microsoft Windows at 80% Active Idle (Suspend-on-Halt)
with a display resolution of 800x600x8 bpp at 75 Hz.
GeodeTM GX1 Processor Internal Block Diagram
Interrupt
Floating Point
Clock Module
SYSCLK
Core
X-Bus
x86 Compatible Core
TLB
Instruction
16 KB
Unified L1
Cache
SYSCLK
X-Bus CLK
(128)
FP_Error
INT/NMI
X-Bus
Power
Management
Control
SUSP#
SUSPA#
Core Suspend
Core Acknowledge
X-Bus Suspend
X-Bus Acknowledge
X-Bus (32)
C-Bus (64)
Write
Read
Display Controller
Timing Generator
INTR
IRQ13
3
REQ/GNT
Pairs
PCI
4
SDRAM
Clocks
64-bit
RGB
YUV
GeodeTM Graphics
S
c
ra
tchp
ad
Arbiter
SMI#
G
eod
eTM
I/O
C
o
mp
ani
o
Clocks
Clocks
Fetch
MMU
Load/Store
Integer
Unit
Unit
Control
Controller
Palette RAM
Compression Buffer
2D Accelerator
ROP Unit
BLT Engine
VGA
Buffers
Buffers
SDRAM
Bus
Arbiter
PCI Host
Controller
multiplied
by "A"
divide by "B"
Companion Interface
April 2000
GeodeTM GX1 Processor Series
Low Power Integrated x86 Solution
National Semiconductor and Virtual System Architecture are registered trademarks of National Semiconductor Corporation.
Geode, WebPAD, and VSA, are trademarks of National Semiconductor Corporation.
For a complete listing of National Semiconductor trademarks, please visit www.national.com/trademarks.
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While the x86 core provides maximum compatibility with
the vast amount of Internet content available, the intelligent
integration of several other functions, such as audio and
graphics, offers a true system-level multimedia solution.
The Geode GX1 processor core is a proven x86 design
that offers competitive performance. It contains integer and
floating point execution units based on sixth-generation
technology. The integer core contains a single, five-stage
execution pipeline and offers advanced features such as
operand forwarding, branch target buffers, and extensive
write buffering. Accesses to the 16 KB write-back L1 cache
are dynamically reordered to eliminate pipeline stalls when
fetching operands.
In addition to the advanced CPU features, the GX1 proces-
sor integrates a host of functions typically implemented
with external components. A full function graphics acceler-
ator contains a VGA (video graphics array) controller, bit-
BLT engine, and a ROP (raster operations) unit for
complete GUI (Graphical User Interface) acceleration
under most operating systems. A display controller con-
tains additional video buffering to enable >30 fps MPEG1
playback and video overlay when used with a National
Semiconductor Geode I/O or graphics companion chip
(e.g., CS5530 or CS9211). Graphics and system memory
accesses are supported by a tightly coupled SDRAM con-
troller which eliminates the need for an external L2 cache.
A PCI host controller supports up to three bus masters for
additional connectivity and multimedia capabilities.
The GX1 processor also incorporates Virtual System
Architecture
(VSATM)
technology.
VSA
technology
enables the XpressGRAPHICS and XpressAUDIO sub-
systems. Software handlers are available that provide full
compatibility for industry standard VGA and 16-bit audio
functions that are transparent at the operating system level.
Together the National Semiconductor I/O companion and
GX1 processor Geode devices provide a scalable, flexible,
low-power, system-level solution well suited for a wide
array of information appliances ranging from hand-held
personal information access devices to digital set-top
boxes and thin clients.
Features
General Features
Packaging:
-- 352-Terminal Ball Grid Array (BGA) or
-- 320-Pin Staggered Pin Grid Array (SPGA)
0.18-micron four layer metal CMOS process
Split rail design:
-- Available 1.6V, 1.8V, or 2.0V core
-- 3.3V I/O interface
Fully static design
Low Typical Power Consumption:
-- 0.8W @ 1.6V/200 MHz
-- 1.2W @ 2.0V/300 MHz
Note:
Typical power consumption is defined as an aver-
age, measured running Windows at 80% Active
Idle (Suspend-on-Halt) with a display resolution of
800x600x8 bpp @ 75 Hz.
Speeds offered up to 300 MHz
Unified Memory Architecture
-- Frame buffer and video memory reside in main
memory
-- Minimizes PCB (Printed Circuit Board) area require-
ments
-- Reduces system cost
Compatible with multiple Geode I/O companion devices
provided by National Semiconductor
32-Bit x86 Processor
Supports Intel's MMX instruction set extension for the
acceleration of multimedia applications
16 KB unified L1 cache
Six-stage pipelined integer unit
Integrated Floating Point Unit (FPU)
Memory Management Unit (MMU) adheres to standard
paging mechanisms and optimizes code fetch perfor-
mance:
-- Load-store reordering gives priority to memory reads
-- Memory-read bypassing eliminates unnecessary or
redundant memory reads
Re-entrant System Management Mode (SMM)
enhanced for VSA technology
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Flexible Power Management
Supports a wide variety of standards:
-- APM (Advanced Power Management) for Legacy
power management
-- ACPI (Advanced Configuration and Power Interface)
for Windows power management
Direct support for all standard processor (C0-C4)
states
-- OnNOW design initiative compliant
Supports a wide variety of hardware and software
controlled modes:
-- Active Idle (core-only stopped, display active)
-- Standby (core and all integrated functions halted)
-- Sleep (core and integrated functions halted and all
external clocks stopped)
-- Suspend Modulation (automatic throttling of CPU
core via Geode I/O or graphics companion chip)
Programmable duty cycle for optimal performance/
thermal balancing
-- Several dedicated and programmable wake-up
events (via Geode I/O or graphics companion chip)
PCI Host Controller
Several arbitration schemes supported
Directly supports up to three PCI bus masters, more with
external logic
Synchronous to CPU core
Allows external PCI master accesses to main memory
concurrent with CPU accesses to L1 cache
Virtual Systems Architecture Technology
Innovative architecture allowing OS independent (soft-
ware) virtualization of hardware functions
Provides XpressGRAPHICS subsystem:
-- High performance legacy VGA core compatibility
Note:
The GUI acceleration is pure hardware.
Provides 16-bit XpressAUDIO subsystem:
-- 16-bit stereo FM synthesis
-- OPL3 emulation
-- Supports MPU-401 MIDI interface
-- Hardware assist provided via Geode I/O companion
chip
Additional hardware functions can be supported as
needed
2D Graphics Accelerator
Accelerates BitBLTs, line draw, text:
-- Bresenham vector engine
Supports all 256 Raster Operations (ROPs)
Supports transparent BLTs and page flipping for
Microsoft's DirectDraw
Runs at core clock frequency
Full VGA and VESA mode support
Special "driver level" instructions utilize internal
scratchpad for enhanced performance
Display Controller
Display Compression Technology (DCT) architecture
greatly reduces memory bandwidth consumption of
display refresh
Supports a separate video buffer and data path to
enable video acceleration in Geode I/O and graphics
companion chips
Internal palette RAM for gamma correction
Direct interface to Geode I/O and graphics companion
chips for CRT and TFT flat panel support eliminates the
need for an external RAMDAC
Hardware cursor
Supports up to 1280x1024x8 bpp and 1024x768x16 bpp
XpressRAM
SDRAM interface tightly coupled to CPU core and
graphics subsystem for maximum efficiency
64-Bit wide memory bus
Support for:
-- Two 168-pin unbuffered DIMMs
-- Up to 16 simultaneously open banks
-- 16-byte reads (burst length of two)
-- Up to 512 MB total memory supported
Diverse Operating System Support
Microsoft's Windows 2000, Windows 95, Windows 98,
and Windows NT in non PC applications; along with
Windows CE and Windows NTE
WindRiver System's VxWorks
QNX Software Systems' QNX
Linux
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Table of Contents
1.0
Architecture Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.1
INTEGER UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.2
FLOATING POINT UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3
WRITE-BACK CACHE UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.4
MEMORY MANAGEMENT UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.5
INTERNAL BUS INTERFACE UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.6
INTEGRATED FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.6.1
Graphics Accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.6.2
Display Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.6.3
XpressRAM Memory Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.6.4
PCI Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.7
GEODE GX1/CS5530 SYSTEM DESIGNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.7.1
Reference Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.0
Signal Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1
PIN ASSIGNMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2
SIGNAL DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2.1
System Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2.2
PCI Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.3
Memory Controller Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.2.4
Video Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2.5
Power, Ground, and No Connect Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.2.6
Internal Test and Measurement Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.0
Processor Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1
CORE PROCESSOR INITIALIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2
INSTRUCTION SET OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.2.1
Lock Prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.3
REGISTER SETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.1
Application Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.1.1
General Purpose Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.1.2
Segment Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.3.1.3
Instruction Pointer Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.3.1.4
EFLAGS Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3.2
System Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.3.2.1
Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.3.2.2
Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.2.3
Debug Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.3.2.4
TLB Test Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
3.3.2.5
Cache Test Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3.3
Model Specific Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.3.4
Time Stamp Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.4
ADDRESS SPACES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.4.1
I/O Address Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.4.2
Memory Address Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
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Table of Contents
(Continued)
3.5
OFFSET, SEGMENT, AND PAGING MECHANISMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.5.1
Offset Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.5.2
Segment Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.5.2.1
Real Mode Segment Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.5.2.2
Virtual 8086 Mode Segment Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.5.2.3
Segment Mechanism in Protected Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.5.2.4
Segment Selectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.5.3
Descriptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.5.3.1
Global and Local Descriptor Table Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.5.3.2
Segment Descriptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.5.3.3
Task, Gate, Interrupt, and Application and System Descriptors . . . . . . . . . . . . . . . . . 71
3.5.4
Paging Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.6
INTERRUPTS AND EXCEPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.6.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.6.2
Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.6.3
Interrupt Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.6.3.1
Interrupt Vector Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.6.3.2
Interrupt Descriptor Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
3.6.4
Interrupt and Exception Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.6.5
Exceptions in Real Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.6.6
Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.7
SYSTEM MANAGEMENT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.7.1
SMM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.7.2
SMI# Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.7.3
SMM Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.7.4
SMM Memory Space Header . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
3.7.5
SMM Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.7.6
SMM Memory Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.7.7
SMI Generation for Virtual VGA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.7.8
SMM Service Routine Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.7.9
SMI Nesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.7.9.1
CPU States Related to SMM and Suspend Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.8
HALT AND SHUTDOWN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.9
PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.9.1
Privilege Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.9.2
I/O Privilege Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.9.3
Privilege Level Transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.9.3.1
Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.9.4
Initialization and Transition to Protected Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.10
VIRTUAL 8086 MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.10.1
Memory Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.10.2
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.10.3
Interrupt Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.10.4
Entering and Leaving Virtual 8086 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.11
FLOATING POINT UNIT OPERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
3.11.1
FPU Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
3.11.2
FPU Tag Word Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
3.11.3
FPU Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
3.11.4
FPU Mode Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
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