SBC-GX1 Technical Manual Detailed hardware description
Processor
The AMD Geode™ GX1 processor is an MMX-Enhanced Pentium class processor. It
has been designed to provide a low power, low cost fully integrated PC/AT compatible
system. The GX1 is a 64-bit x86 compatible device and has 16K L1 write-back cache
integrated into the processor. The device also contains an integrated floating point unit.
A 300MHz part is used on the SBC-GX1, this part is supplied with a 33MHz clock signal
and multiplied within the device.
The processor has two supply rails the core is powered from a +2.0V source and the
I/O is powered from +3.3V. These voltages are generated on the SBC-GX1 from the
main +5V supply input.
Along with the CS5530 I/O companion chip the GX1 provides a Synchronous DRAM
controller, VGA Video Controller, PCI 2.1 compatible bus controller, 32-bit IDE controller,
SoundBlaster compatible Audio device, PCI-ISA bus bridge, standard ISA bus
motherboard peripherals and a dual USB controller.
The GX1 processor is packaged in 352 pin ball-grid-array (BGA), and therefore is
attached to the board during the assembly process. The board will be configured with
the correct voltage setting and clock selection for the processor.
The GX1 processor is a low power device and a passive heatsink has been used to
support this device on the SBC-GX1. This heatsink provides the correct heat dissipation
to enable the processor to operate at ambient temperatures up to 60
o
C (140
o
F).
Memory
The SBC-GX1 supports three types of memory device - the system memory that is
provided by a Synchronous DRAM module, the BIOS EPROM, and the Flash memory.
Further details about each are provided below.
Synchronous DRAM Interface
A single 144-pin Small Outline Dual Inline Memory Module (SODIMM) socket, DIMM1,
provides support for up to 256M bytes of synchronous DRAM. This interface is
designed to support 16MB, 32MB, 64MB, 128MB and 256MB modules which are 3.3V
compatible and meet the PC100 or PC133 timing specification. The SODIMM socket is
designed to ensure that only the correct type of memory is installed.
The BIOS automatically detects the amount of memory inserted into this socket during
the power up process, and sets up the appropriate registers correctly with the Geode™
GX1 processor. The BIOS can also be configured to perform an exhaustive test on this
memory during the POST process to ensure it is functioning correctly. This does,
however, increase the boot time.
The performance of the SBC-GX1 can be improved by selecting the correct type of
memory. The board supports two memory speeds 75MHz (divide by 4) or 100MHz
(divide by 3). Due to the design of the AMD Geode GX1 processor, the memory used
must be rated above the nominal operating frequency. Therefore if the memory bus
© 2004 Arcom Issue D 63
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