Developers can’ t get
enough processing power,
memory, and I/O ports. Of course,
having them on-chip is just the
start. Getting them connected to do
useful work is another matter. Modular
techniques have led to a range of form
factors, from board-level systems such as
VME to modules like COM Express.
The VIA Technologies Em-ITX form
factor is designed to bring lots of I/O ports
to the outside world with dual I/O port
coast lines. The EITX-3000, the first entry
for this form factor, incorporates a 1.3-
GHz VIA Nano processor and the Em-IO
expansion connector (Fig. 1). I/O interfaces
include an 8-bit digital port, a VGA
port, dual low-voltage differential signaling
(LVDS) ports, dual Gigabit Ethernet,
four serial ports, dual SATA II ports, six
USB 2.0 ports, and HD audio. It can handle
up to a 2-Gbyte DDR2 SODIMM. A
Compact Flash socket is on the bottom.
The entire case is an aluminum heatsink.
It supports a range of power inputs, from 7
V to 36 V dc. VIA has three expansion
boards that plug into the Em-IO connector.
One adds Wi-Fi support, the second
adds more serial and parallel ports, and the
third adds video including HDMI support.
There is sufficient space inside the system
for a 2.5-in. hard drive.
Em-ITX is another form factor to add
to the list. It brings a lot of connectors to
both sides of the system. Most motherboard
form factors such as Mini-ITX and
Micro ATX only have connectors on
one side.
TOO MANY FORM FACTORS
So what’s one more form factor when
there are dozens to choose from? Each was
designed for a purpose, such as supporting
standard expansion cards either in slots
like PCI and PCI Express cards for a PC or
in stackable systems such as PC/104. Form
factors tend to fade away as bus standards
migrate to new technologies. There are
no Multibus I (IEEE 796) boards around
these days since single-chip micros can
run rings around their 20-bit transistortransistor
logic (TTL) address bus.
Yet simple interfaces die hard. The venerable
ISA bus that started the PC revolution
is still found in PC/104 boards.
Newer incarnations such as VersaLogic’s
Ocelot SUMIT-104 (Fig. 2) employ the
Small Form Factor SIG SUMIT interface
(see “SUMIT Brings Big Improvements
In Small Packages” at www.electronicdesign.
com, ED Online 18687). SUMIT is
a stackable system featuring a number of
interfaces, including PCI Express, LPC,
USB, and SMB. The SUMIT-104 designation
means the single-board computer has
a SUMIT- and a PC/104-compatible ISA
connector.
SMALL FORM FACTOR SIG
www.sff-sig.org
VERSALOGIC
www.versalogic.com
VIA TECHNOLOGIES
www.via.com.tw