Geode™ GXm Processor Integrated x86 Solution with MMX Support
April 2000
Geode™ GXm Processor
Integrated x86 Solution with MMX Support
General Description
The National Semiconductor
®
Geode™ GXm processor
is an advanced 32-bit x86 compatible processor offering
high performance, fully accelerated 2D graphics, a 64-bit
synchronous DRAM controller and a PCI bus controller,
all on a single chip that is compatible with Intel’s MMX
technology.
The GXm processor core is a proven design that offers
competitive CPU performance. It has integer and floating
point execution units that are based on sixth-generation
technology. The integer core contains a single, six-stage
execution pipeline and offers advanced features such as
operand forwarding, branch target buffers, and extensive
write buffering. A 16 KB write-back L1 cache is accessed
in a unique fashion that eliminates pipeline stalls to fetch
operands that hit in the cache.
In addition to the advanced CPU features, the GXm pro-
cessor integrates a host of functions which are typically
implemented with external components. A full-function
graphics accelerator provides pixel processing and ren-
dering functions.
A separate on-chip video buffer enables >30 fps MPEG1
video playback when used together with the CS5530 I/O
companion chip. Graphics and system memory accesses
are supported by a tightly-coupled synchronous DRAM
(SDRAM) memory controller. This tightly coupled memory
subsystem eliminates the need for an external L2 cache.
The GXm processor includes Virtual System Architec-
ture
®
(VSA™ technology) enabling XpressGRAPHICS
and XpressAUDIO subsystems as well as generic emula-
tion capabilities. Software handler routines for the Xpress-
GRAPHICS and XpressAUDIO subsystems can be
included in the BIOS and provide compatible VGA and 16-
bit industry standard audio emulation. XpressAUDIO tech-
nology eliminates much of the hardware traditionally asso-
ciated with audio functions.
Geode™ GXm Processor Internal Block Diagram
Write-Back
Cache Unit
C-Bus
MMU
Integer
Unit
FPU
Internal Bus Interface Unit
X-Bus
Integrated
Functions
Graphics
Pipeline
Memory
Controller
Display
Controller
PCI
Controller
SDRAM Port
CS5530
(CRT/LCD TFT)
PCI Bus
National Semiconductor and Virtual System Architecture are registered trademarks of National Semiconductor Corporation.
Geode 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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