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4 Feature Reference
This chapter provides details about the architecture and many features of the BitsyXb, and how
they can fit together to create a system that meets your application needs.
4.1
System Architecture
This section describes the core functionality of the BitsyXb.
4.1.1
Boot Code
The BitsyXb uses the first block of onboard flash to store the boot code. At the factory, boot code
is loaded using the JTAG interface (J16, section 3.3.9). Most Eurotech BitsyXb boot loaders are
field-upgradeable using a flash card on either the CompactFlash or PCMCIA port.
4.1.2
Synchronous DRAM
The BitsyXb uses synchronous DRAM (SDRAM) for kernel, application and display frame buffer
use. The data bus width is 32 bits. The memory clock speed is one half the CPU core clock
speed. Typical memory bus operation is at 99.5 MHz.
The self-refreshed RAM consumes most of the system sleep current. Sleep current increases
roughly in direct proportion to the amount of RAM installed.
4.1.3
Non-Volatile Memory
There are several ways to store data on the BitsyXb that will survive a power failure. Some
devices can only be accessed through operating system drivers, and not all are available for
application data storage.
Flash Memory
Flash memory is the primary site for non-volatile data storage. The BitsyXb includes flash
memory for non-volatile data storage. The data bus width is 32 bits.
Eurotech systems store the operating system, applications and system configuration settings in the
onboard flash. Most operating systems configure a portion of the flash as a flash disk, which acts
like a hard disk drive.
ADSmartIO EEPROM
The ADSmartIO controller includes 256 bytes or more of EEPROM storage. Eurotech reserves a
portion of this memory for future use. Drivers are not yet available for all operating systems.
CompactFlash and PCMCIA/ATA Cards
CF and ATA cards provide removable storage in a wide variety of capacities. These cards can be
a cost-effective means to expand system storage capacity for applications that provide access to
the PCMCIA and CF slots. A CF slot must be placed on a daughter board, as it is not included on
the BitsyXb.
