Aerospace and military applications
that are more sophisticated
and complex are spawning a new
breed of single-board computers
(SBCs). That’s because the users in
these areas have rather formidable
demands, such as greater ruggedness,
higher reliability, more power
performance, less power dissipation, and a smaller form factor.
As a result, board and systems integrators are
scrambling to find ways to pack as much technology
as possible on the smallest board practical.
Some companies are using commercial
off-the-shelf (COTS) technology. Others are
employing multicore designs, in which a board
may have several processors, some coming from
different manufacturers.
Designers use a range of operating systems as
well, often utilizing multiple operating systems
like Unix, Linux, Microsoft’s Windows XP
Pro and Embedded, and Wind River Systems’ VxWorks on a
single board. In addition, high-speed serial buses are favored
over older parallel buses to handle the higher-data-rate and
wider-bandwidth communications of modern SBCs.
Although COTS components see wide use in SBC designs,
their application sometimes depends on performance requirements
and the design budget. Some SBC designs requiring
very high performance levels may opt to use custom components
should the design budget allow it.
Multicore COTS processing that incorporates leadingedge,
high-performance processors promises to revolutionize
SBC designs. The multicore approach eliminates the need for
individual computer boards for each application. It also allows
multiple applications to run from a single board, often from a
single CPU. High-performance multicore processors can be
found in many SBCs and plug-in support mezzanine cards.
MULTICORE COTS PROCESSING
These multicore processors include Analog Devices’ Sharc and
Blackfin; Freescale Semiconductor’s 8641 PowerPC and 8555E;
Intel’s Core 2 Duo, Xeon Dual, and Pentium; AMD’s Turion 64,
Opteron, and Radion HD3650; Sun Microsystems’ UltraSPARC
IIi and IIIi; PA Semiconductor’s 1682; and the MIPS64 from
Cavium Networks.
Jointly developed by Sony Computer Entertainment, Toshiba,
and IBM, the Cell Broadband Engine (Cell BE) multicore processor
architecture from supplier IPV Ltd. combines a modest
general-purpose Power Architecture core with streamlined
co-processing elements that greatly accelerate multimedia and
vector-processing applications, as well as many other forms of
dedicated computation (Fig. 1).
Ruggedness is a key parameter for aerospace and defense users
of SBCs. With a 3U CompactPCI design, the S950 SBC developed
by Aitech Defense Systems uses as little as 13.5 W in full
operation and less than 8 W in sleep mode. It’s based on a PowerPC
750FX platform and features a radiation-tolerant anti-fuse
FPGA that maintains memory control to ensure data integrity in
harsh environments.
General Micro Systems also uses the CompactPCI approach
in its Premonition CC279. This 6U, 100-W, conduction-cooled
SBC is based on the user’s choice of two Intel Quad-Core or two
Dual-Core Xeon processors (Fig. 2).
The use of field-programmable gate arrays (FPGAs) is another
rising trend in SBC designs. FPGAs not only provide the required
number-crunching and interfacing with high-speed serial buses,
they also ease a designer’s migration from older-generation,
FPGA-based designs without having to worry about the requirements
for lead-free components.
An SBC can form an entire system on a
board for a specific function. Or, several SBCs
can be plugged into a backplane connector within a
box-like metal cage for even higher performance. Some of these
SBCs may not abide by SBC standards, though, since they may
be entirely custom-made. Also, many specific-function mezzanine
cards can plug into SBCs, like graphics accelerator mezzanine
cards, display and other types of mezzanine controller cards, and
memory mezzanine cards.
Developed by Mercury Computer Systems, the PowerBlock
50 crams a tremendous amount of power into a box-like product
(Fig. 3). This 6- to 10-lb unit measures just 4 by 5 by 6 in.,
yet it delivers 100 GFLOPS of processing power. Optimized
for embedded computing applications where space and weight
constraints are important, the PowerBlock 50 uses the Cell BE
multicore processor.
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