User`s guide

T-MOPSlcdSA User's Guide
Introduction 6
6
2.3 PC/104 an Embedded PC Standard
Over the past decade, PC architecture has become an accepted platform for far more than desktop
applications. Dedicated and embedded applications for PCs are beginning to appear everywhere.
By standardizing hardware and software around the broadly supported PC architecture, embedded
system designers can substantially reduce development costs, risks, and time-to-market.
For these reasons, companies that embed microcomputers as controllers within their products seek
ways to reap the benefits of using the PC architecture. However, the standard form factor of a PC
bus (12.4" x 4.8") and its associated card cages and backplanes are too bulky and expensive for
most embedded control applications.
The only practical way to embed the PC architecture in space-and power-sensitive applications has
been to design a PC chip by chip directly into the product. But this runs counter to growing trend
away from "reinventing the wheel." Whenever possible, top management now encourages
outsourcing of components and technologies to reduce development costs and accelerate product
design cycles.
A need has arisen for a more compact implementation of the PC bus, satisfying the reduced space
and power constraints of embedded control applications. PC/104 was developed in response to
this need. It offers full architecture, hardware and software compatibility with the PC bus but in
ultra-compact (3.6" x 3.8") stackable modules. PC/104 is ideally suited to the unique
requirements of embedded control applications.
Although configuration and application possibilities with PC/104 modules are practically limitless,
there are two ways to use them in embedded system designs:
 Standalone module stacks
PC/104 modules are self-stacking. The modules are used like ultra-compact bus boards but
without a need for backplanes or card cages. Stacked modules are spaced 0.6 inches apart.
(The three-module stack measures 3.6 by 3.8 by 2 inches.) Companies using PC/104
module stacks within their products frequently create one or more of their own application-
specific PC/104 modules.
 Component-line applications
In this configuration, the modules function as highly integrated components, plugged into
custom carrier boards that contain application-specific interfaces and logic. The modules'
self-stacking bus can be useful to install multiple modules in one location. This facilitates
product upgrades or options and allows temporary addition of modules during system
debug or test.