Things have really taken off recently. This page provides a starting point.

Avoid WinCE. It is flawed in concept, and the reports on its practical use are pretty bad as of Jan'98. Linux or NetBSD is a better choice. Linux is embeddable with real-time hooks (see the Linux Journal) and still every bit as powerful as its desktop version because, well, it IS the desktop version. Makes development, support, and upgrades trivial. No threat of a company stopping support/development (as what has happened with Windows Lite and Windows for Pens), because you can keep a copy of the (free) source code to compile 20 years from now. In addition, there are many companies supporting it instead of just one. Other choices are Microware's OS9 (traditionally technically excellent over the long term) and VxWorks (used in the Mars mission I think).

The PC/104 and PC/104+ Standards

PC/104 is an ISA-based embedded computer standard. PC/104+ is an extension that includes a second, 32 bit PCI-based bus. The boards tend to be around 3.6" x 3.8" x 0.9" with connectors that allow you to stack them up or across lego-style. There are hundreds of vendors. Here is an excerpt on The Need for an Embedded-PC Standard This is a very fertile area for those experimenting in wearable computers , robotics , car-based systems , or anyplace else small computers are needed.

Adaptive Systems alternative

Adaptive Systems produces 2"x3.5" stackable boards with many of the features of PC/104. Excellent when size matters most.

Some indexes to PC/104 vendors


Generally, the Lizzy has used Enclosure Tech's half cube. However, the new IDAN by RTD looks very interesting.

Board set manufacturers:

Specialty boards:



Haven't played with Comark's boards yet, but they have the highest end processor at a 133Mhz Pentium with 32M RAM. However, this .75" height board has to be the top in the stack due to cooling: 8-9W without RAM I believe. Unfortunately, these CPU modules ONLY include the CPU and keyboard....serial, parallel, etc. you need another board.

Megatel tends to be more sophisticated in its technology, but research what you are getting before you buy. Definitely worth keeping an eye on. Supposedly the base Megatel board, which includes Ethernet, can be used with Linux if you recompile with Intel Ether Express Pro support turned on. However, we've had flakiness with this code, so this still seems not to be an option. More when we get one to eval. For the most part, only CPU modules. Tend to be slightly bigger (4"x4") than normal PC104's (3.6"x3.8")

Ampro tends to be reliable with moderate sophistication. Generally good experiences with these products. Definitely the way to start out, because they are so fast to prototype. Runs Linux no problem. Full line.

Arize tends be a bit slower on the new tech but cheaper. CPU modules and some support.

Advantech has a full line, but is really lacking on the CPU. Highest end as of 2/6/96 was a 33Mhz 386 with 4M RAM. However, they do make some nice support modules. For example, they keep a 1M VRAM SVGA board in stock (Ampro is a special order only) so that you can do 640x480x24 bits. Also, they have a 4 serial port board and a floppy, IDE, and 2 serial board.

RTD has a nice full line, with some additional features on their CPU board that Ampro does not have, but these features are at the cost of system RAM-only 4M. The maximum these systems have is 8M. However, if memory is not a problem for you, this is probably the way to go. Interesting data acquisition and control modules.

A warning about PC104: While we haven't had any troubles, supposedly most companies are only 90% compatible with the written spec. This is the same problem PCMCIA is having right now. Insist on good specs! Also, some of the PC104 cards can only be at the top or bottom of the stack, they do not contain the pass through connectors. Be particularly aware of Megatel CPU boards and Private Eye driver boards for this. When ordering, be explicit that you are interested in a board for a PC104 16 bit (some only do 8...earlier standard) stack-through system.

Take a look at some PC104 system boards:
pc104 486 core module
pc104 VGA board
pc104 floppy and IDE controller board

Take a look at a PC104 system being assembled

Last modified: Mon Jun 1 23:15:04 EDT 1998