single board computers

The demand for small, reliable and compatible microcomputers is creating an expanding market for STD bus products as customers look for either a single board they can embed or a complete system in a small card cage with a few slots. Many of the boards provide connections for hard and/or floppy disks, video ports, digital I/O, keyboard interfaces and parallel or serial ports. Some STD vendors provide systems that are on only one card while others use a mother/daughter board to make room for more functions. Compactness is a critical factor for many applications and STD vendors are attempting to compact designs further, squeezing in as many functions as possible. Boosting performance is another goal; there is talk of an 80486 STD product in the works.

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STD Bus, with and without the 32-bit extension, continues on a roll as demand sur s for small, reliable PC compatibles. The latest round of STD Bus products reflects that demand-80286 and 80386 SX machines have entered the market, rivaling the best of the desktop units in performance while exceeding them in reliability, ruggedness and compact size. What's more, 386 DX and even 486 STD boards are on the drawing board-and in one case, already in the breadboard stage.

"Customers are looking for compact solutions to embedded control problems in both DOS and Unix environments," says Jim Eckford, director of marketing for Ziatech (San Luis Obispo, CA). According to Eckford, some customers are looking a complete system in a small card cage with only a few slots, while others are looking for a single board they can embed in their products. "Either way, customers are looking for smaller yet more powerful STD solutions," he says. "Size is turning out to be the most important feature of STD Bus."

As a result of the demand, an entire new family of STD products has been emerging over the past year, sporting high-performance processors, memory, and as much assorted I/O as will fit on the small form-factor card. In addition, many of these boards provide hard and/or floppy disk interfaces, some kind of video port, some digital I/O, a keyboard interface and at least a serial or parallel port.

Kurt Priester, president of Computer Dynamics (Greer, SC), one of the many companies offering high-performance PC-compatible machines on STD, agrees with Eckford about the rising demand for small form-factor PC compatibles, but adds that "the other critical component in the formula is quality." Priester maintains that many PC applications fall from grace as the PCs prove unreliable.

"It's not uncommon," says Priester, "for companies to develop systems based on a conventional desktop PC only to have downtime wipe out all the gains made by automating a process. So many designers are turning to STD for the added reliability-the reduced size is simply an added bonus. With the latest generation of high-performance machines available on STD, there's no need to sacrifice performance or features to switch to STD."

WinSystems (Arlington, TX) is another of the STD makers that has been one of the leaders of the highperformance PC-compatible bandwagon. Me advanced PC chip sets provide the necessary functionality and space savings to allow complete PCs to reside on a single STD board," says Bob Burckle, WinSystems director of marketing. The Chips and Technologies chip set that we use not only provides the housekeeping and peripheral functions for the PC but also provides clock signals to allow the processor to zip along at'. its top speed internally, while the backplane is allowed to operate at another speed. This means that the processor's performance isn't impaired by the relatively slow STD Bus, which isn't the case with some other solutions,' he says. I Slight differences Interestingly, the various approaches taken by STD vendors making PC compatibles differ only slightly. Computer Dynamics, for example, in its CPU-AT provides a 25-MHz 286based board with up to 4 Mbytes of memory, and the company claims that the CPU-AT is 100 percent PC/AT compatible. In addition to the processor and memory, the board has room for a 256-kbit EPROM, two RS-232 ports, a printer port, a floppy disk controller, an IDE hard disk interface, a battery-backed real-time clock and CGA, EGA or VGA video. Furthermore, Priester claims that it's one of the few STD CPUs set up to drive flat-panel displays including LCD, plasma, electroluminescent and vacuum fluorescent.

The entire system, however, doesn't reside on only one card. The processor, memory, I/O ports and EPROM reside on one board, while the video, Winchester and floppy controllers reside on a daughtercard that plugs directly onto a connector on the host processor board. This dual-board approach was taken for two reasons," says Priester. "First, there just isn't enough room on the processor board for the rest of the functions and the mother/daughterboard is a good way to make more room. Second, many customers simply want to embed the processor and memory functions with or without a card cage. The CPU-AT processor module permits that without the expense of including the disk and video interface functions.

"Right now, we're using the 286 processor because it offers equivalent-or better-performance than the 386 SX at a lower price," Priester says. "Unless the advanced memory features offered by the 386 SX are critical, there's no reason that I can think of to use the SX." But the 386 DX is a different story, according to Priester, and he expects his company to develop a 386 DX machine soon.

WinSystems also provides a high-performance 286-based machine with similar functions. And this company, unlike Computer Dynamics, offers a board using a 16- or 20MHz 386 SX. WinSystems' 386 SX board allows for automatic switching between 8- and 16-bit transfers and, like other approaches, separates the disk and video interface from the main processor board. A specially modified Phoenix BIOS allows the board to boot off either disk or ROM.

* STD 32 Ziatech, not unexpectedly, used the company-developed STD 32 for its latest 386 CPU board. STD 32 has been on a popularity roller coaster since Ziatech first announced it almost a year ago. It still has only a limited following, and some supporters who had initially expressed a favorable response, such as Computer Dynamics' Priester, have recently displayed considerably less enthusiasm. Further, the STD Manufacturers Group appears to be no closer to endorsing the concept than it was six months ago.

Despite the ups and downs, Ziatech and a small group of vendors calling themselves Task Group 32 have gone ahead and finalized the specification, provided nonrecurring engineering expense monies for the manufacture of the connector, designated a connector manufacturer, and set up licensing rules. In addition, the group has cleared the use of the EISA specification and settled other legal issues that could have been obstacles. Still, reception to STD 32 has been cool at the STD vendor level due to what Priester describes as "political problems."

Though connectors and backplanes for STD 32 won't be available until October, Ziatech has been making its CPU board for some time. "You have to remember that STD 32 is fully compatible with all existing 8-bit backplanes and systems," s Eckford. Ziatech's 386 SX-based CPU approach is similar to Computer Dynamics' and WinSystems' in that it uses two boards: one for processor/memory and another for video and disk control.

Ziatech's processor/memory board is a full 32-bit 386 SX with 8 Mbytes of memory, a pair of serial ports, a parallel port, a keyboard interface and all the other features normally found on a CPU. A companion card includes the floppy disk and hard disk controllers and VGA port. These two boards combined with a floppy disk drive and a 40- or 105Mbyte Winchester make an attractive package," says Eckford, "and it fits in a five-board STD card cage. Complete, the package is 7 in. wide."

* Looking ahead

Ziatech's existing package is only the tip of the iceberg, according to Eckford, who says his company realizes that board compactness is critical to many applications and is compacting its designs even further. Ziatech will soon unveil a 286-based card with even more I/O than existing cards. To squeeze in the additional functionality, the company is taking advantage of its recently developed ASIC I/O chip designed to provide high-density, high-current digital I/O.

The 286 board is expected to boast 48 digital I/O points in addition to memory, serial and parallel I/O. "The digital I/O chip we developed is just the first of many we plan to develop to increase functionality on the postcard-sized STD form factor," says Eckford. "Even though the chip was used in a few current products and will be incorporated into several emerging products, it was really a test-bed for our ASIC strategy, and we expect to be developing more custom chips."

While STD vendors are looking to compact more functions on their boards, they also have an eye toward boosting performance. Computer Dynamics and WinSystems are running 286-based machines at 20 and 25 MHz, and WinSystems and Ziatech are running 386 SX boards at 16 and 20 MHz. Computer Dynamics, as mentioned, is planning to develop a high-speed 386 DX machine soon, while Ziatech may well jump the gun and offer a 486 machine in the not-too-distant future.

"Right now, it's too early to tell whether-or when-a 486 STD product will emerge," says Eckford, but we have a breadboard of a full 486 EISA machine already completed. Since STD 32 operates on a subset of the EISA specification, an STD 32/EISA design could become a reality in a relatively short time."

And some vendors that are looking to stretch the performance envelope are also looking to put STD/PC power in customers' hands at increasingly lower prices. "WinSystems has just announced a new low-priced CPU for those embedded applications calling for moderate PC performance at a moderate price," says Burckle. Based on an 80188 processor, the WinSystems board is priced under $200.



Source Citation:Andrews, Warren. "Small, reliable STD SBCs move into PC territory." Computer Design 29.n17 (Sept 1, 1990): 66(3). Computer Database. Gale. BROWARD COUNTY LIBRARY. 10 June 2009
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