PCs are spreading their wings. Not only are they sitting on millions of desktops and laptops in businesses, homes, and schools, but they're hiding in such applications as vending machines, laboratory instruments, and communications and medical devices.

Using the IBM PC architecture, embedded-system designers can reduce development costs, risks, and time to market. If the target system is truly PC compatible, they know their software will run after they write it on the desktop. Another critical advantage: The PC's widely available hardware and software usually prove far more economical than those of traditional embedded buses, such as the STD, VME, and Multibus.

Putting a PC to bed. You can embed a PC two ways: Use a PC motherboard, or buy a single-board computer designed for embedding. Most designers opt for the second route. Standard PC motherboards and associated card cages and backplanes contain too much bulk for most embedded control applications.

So companies such as Ampro, WinSystems, and Epson have miniaturized the PC-without losing any of its functionality. These boards range from 80386-, 80486-, and Pentium-based units, nearly identical to the motherboard versions, to the lower-end 8088, 80186, and 80268 boards, which are more specialized.

Torrance, CA-based Epson has shrunk the PC motherboard into a package the size of a credit card. Ampro Computers, Sunnyvale, CA, originated the PC/104 form factor, which WinSystems in Arlington, TX, and other companies also offer. These modules measure 3.6 x 3.8 inches (about the size of a 5.25-inch floppy-disk drive), and can be stacked and connected through a PC-compatible bus. In addition to CPU modules, PC/104 modules drive displays, accept PCMCIA cards, and add serial ports. They also attach to non-PC/104 boards that have the 104-pin connectors.

In tune with the electronics industry, embedded PCs continue to get smaller, faster, and cheaper. Designers are already embedding Pentiums and taking advantage of the PCI bus to move 32-bit data.

One place PCs are hiding is in airplanes. ARNAV Systems, Inc., Pu-yallup, WA, supplies the ICDS 2000 Integrated Avionics SmartSuite for the ST-50 aircraft. The single-pilot, 5-seat, all-weather business executive aircraft will sell for about $1,000,000. Designed by Cirrus Design Corp., Duluth, MN, it's made in Tel-Hai, Israel, by Israviation, a subsidiary of Luxembourg-based Euroaviation SA Holding. The company expects FAA certification of the aircraft in 1996.

In the ST-50, the ICDS 2000 serves as an instrument panel, and is controlled by a CoreModule/486 from Ampro Computers, Inc. The panel will have four 8 x 6-inch LCDs: the left- and right-side. Primary Flight Displays (PFD), left-center Multi-Function Display (MFD), and right- center Engine Instrument/Crew Alerting System (EICAS) Display.

The PFDs present standard horizon, attitude, airspeed, altitude, and directional guidance information. They can also display landing gear, flaps, and ground proximity annunciators.

The MFD features a moving map for situational awareness. Weather Radar, lightning, turbulence, icing, floor, ceiling, and visibility graphics are "painted" around the aircraft symbol on the moving map.

In addition to performing traditional engine monitoring, the EICAS-using NASA software-automatically compensates for changes in aircraft performance caused by altitude, temperature, drag, and engine aging.

The Flight Management System includes sensors for Loran and the Global Positioning System (GPS)-a series of satellites that uses triangulation methods to calculate latitude, longitude, and altitude. A 512-kbyte, solid-state disk stores geographical data such as rivers, mountains, and state boundaries.

PCMCIA cards-called Jeppesen NavData Cards-provide data on airports, navaids, and approaches. An optional PCMCIA DataCard can store up to 64 Mbytes of information, including terrain and manmade obstacles. PCMCIA devices are ideal for embedded applications-they're small, rugged, and low power.

Lynn Johnson, director of engineering at ARNAV, says that previous designs had used a microcontroller. "But for this project, an embedded PC fit our needs more precisely because of the graphics environment and the modular approach," he explains. Such modularity, he adds, lets ARNAV reuse the hardware and the software for future designs. This, in turn, results in "faster time to market because you don't have to re-engineer the PC."

There are some drawbacks, however, such as developing the software operating system. "We developed the application on DOS using a PC," Johnson reports. "But we run it under our own operating software. For FAA certification, you need access to the source code, which Microsoft won't give you."

In any event, ARNAV would have to write its own software. "You still don't lose the advantage in the development cycle because you can prove your concepts and algorithms independent of the operating system. When you compile the code to execute in the target environment, you're testing your operating system and how it interfaces with the software you've already proven."

The Ampro PC/104 modules ARNAV uses are the CoreModule(TM)/486-II and the MiniModule(TM)/VGA-FP for controlling the flat-panel displays. The CoreModule packs a 50-MHz 486SLC microprocessor, bootable solid-state disk, keyboard port, real-time clock, and programmable watchdog timer. Right now, ARNAV is using its own PCMCIA module, but is evaluating Ampro's PC/104 MiniModule/PCMCIA, which would stack on top of the other two.

Averting disasters. CAST, Los Alamitos, CA, turned to embedded PC products from WinSystems to develop the ADS Navigator for ship safety. The product, a navigation and position-reporting unit, employs the GPS.

Running under DOS, the device provides Vessel Traffic Systems and other marine location systems with current, accurate information on a vessel's identity, location, speed, course, and even Lloyd's of London registration number. When the vessel enters designated waters, the VHF-FM transceiver automatically responds to a Vessel Traffic Center with this data. The unit also features a display for harbor exit and entrance.

The technology was prompted by the Exxon Valdez accident that spilled nearly 11 million gallons of crude oil into Prince William Sound in Alaska. The clean-up still continues. Law now mandates that all oil tankers that go in and out of the sound use such automated dependent surveillance equipment to insure safety and protect the environment.

The shipboard unit consists of a 12-channel GPS receiver, a marine beacon receiver to receive GPS corrections, a control/display computer with several ports, a power supply, and a liquid-crystal display with a touch screen. The embedded PC lets the unit operate independent of the other ship equipment, but it can also be integrated with the ship's heading. Also on board the unit are the connectors for the GPS and marine receiver antennae and the VHF-FM receiver.

The GPS receiver automatically accepts differential corrections from a built-in marine band nondirectional beacon receiver. This information lets the device refine GPS accuracy from 100 meters to less than 10 meters.

Associate Engineer John Clark III helped design, build, and install the hardware. It now resides in oil tankers operated by ARCO and British Petroleum that ply the Alaskan coastline.

Why embed a PC? Answers Clark: "We have a lot of serial ports that communicate with different products in our unit, such as the beacon receiver, interactive display, radio, and GPS unit. The embedded design lets us do our own navigation and run independently of other ship systems. Also, we can interface the device to existing ship equipment, such as heading sensors and the radar system."

Clark adds that he couldn't use a microcontroller for the job because of the intensive data processing and the control lines. "The PC gives us more flexibility, a lot more control, and the ability to change the application as needed." CAST licenses MS-DOS 5.0, but just uses the basic command structure.

The WinSystems products inside the ADS Navigator include the SAT-486SLC-33 CPU board and the PCM-COM4 serial-port module. The CPU board measures 4.5 x 7.1 inches and is based on a 33-MHz Intel 486SLC. On-board peripherals include a real-time clock, two serial ports, one parallel port, keyboard controller, disk-drive controllers, PC/104 connector, and 4 Mbytes of dynamic RAM. "We add another 1 Mbyte of static RAM to embed our code, instead of using a hard-disk drive, and put the BIOS in ROM," says Clark.

The PCM-COM4-a rugged, low-power PC/104 module-provides four serial ports that transmit data at speeds up to 115.2 kbits/sec.

You wear it well. Another company that enjoys the benefits of embedding a PC is The Flexible PC Co., Northfield, MN. It has developed a PC "on a belt" for on-the-go applications. The company has fashioned the design as a belt, suspenders, holster, vest, and bandoleer.

The "ViA" consists of a flexible circuit board that interconnects a computer processor card, series of PCMCIA cards, standard I/O ports, docking port, and a flexible, rechargeable lithiumion polymer battery. Units can function independently with on-board memory or as network nodes.

The system also comes with miniature display options: eyeglasses, projected display or heads-up display. However, the product's real advantage is its hands-free operation based on voice recognition.

"ViA is ideal for those on-the-go people who require information on demand, anywhere, anytime," says company president David Carroll. He cites such applications as safety reminders and verification, training, stock and inventory management, and equipment operation.

Epson America's Cardio miniature motherboards serve as the system's heart. Flexible PC uses both 386- and 486-based cards. Both versions include ROM and RAM and VGA, keyboard, and floppy-disk-drive controllers. Although the same size as a PCMCIA card (85.6 x 54 x 5.5 mm), Cardio connects to the flexible circuit board via a side-mounted, 236-pin connector. (PCMCIA cards have end-mounted, 68-pin connectors.)

The embedded-PC approach means designers can upgrade the processor by simply replacing the card and can add lots of peripherals via PCMCIA cards. Here's a sampling of PCMCIA cards already available for ViA: wireless LAN nodes, hard-disk drives, flash memory, cellular phone, digital camera, sound card, sensor cards, modem, pager, and a voice-recognition system. Units should be available this summer.

Growing market. In 1993, the worldwide market for embedded PCs totalled $160 million. That breaks down to 132,000 units sold, says Don Carey, service director at market-research firm Venture Development Corp., Natick, MA. He estimates the 1994 market at $185 million with an annual growth rate of 12.7% through 1997.

"The leading application areas are industrial automation, communica-tions, medical, and transportation," he says. Carey also advises keeping an eye on the communications sector in the near future: "Embedded PCs in telecommunications applications could really take off."