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National Semiconductor |
April 2000
Geode™ GX1 Processor Series
Low Power Integrated x86 Solution
General Description
The National Semiconductor® Geode™ 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-
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and business professionals alike, it’s the perfect
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.
Geode™ GX1 Processor Internal Block Diagram
SYSCLK
Clock Module
SYSCLK
multiplied
by “A”
Core
Clocks
X-Bus
Clocks
16 KB
Unified L1
Cache
(128)
C-Bus (64)
x86 Compatible Core
Integer
TLB Unit
Instruction
Fetch
MMU
Load/Store
INT/NMI
Interrupt
Control
FP_Error
Floating Point
Unit
INTR
IRQ13
SMI#
SUSP#
SUSPA#
Power
Management
Control
Core Suspend
Core Acknowledge
X-Bus Suspend
X-Bus Acknowledge
X-Bus (32)
Arbiter
Write
Buffers
X-Bus
Controller
Read
Buffers
Arbiter
PCI Host
Controller
2D Accelerator
VGA
BLT Engine
ROP Unit
X-Bus CLK
divide by “B”
Display Controller
Compression Buffer
Palette RAM
Timing Generator
3
REQ/GNT
Pairs
PCI
Bus
4
SDRAM
Clocks
64-bit
SDRAM
RGB
YUV
Geode™ Graphics
Companion Interface
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.
© 2000 National Semiconductor Corporation
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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
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components. A
a VGA (video
full function graphics acceler-
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® (VSA™) 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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