Several years ago, when the Microsoft SNA server appeared on the scene, Bus-Tech started building drivers enabling it to talk to Bus-Tech adapters and provide very high-speed connections between Windows NT servers and IBM mainframes. Then, when Microsoft announced Windows NT Embedded, Bus-Tech saw the opportunity to combine its existing software technology with inexpensive commercially available hardware to satisfy an unmet need in the market.
Because of gradual obsolescence, a hole had appeared in the company's product set-there was no low-cost TCP/IP controller that did Escon-to-fast Ethernet connections. Bus-Tech had built its older product on proprietary hardware and firmware, which increased costs and development time.
While the company was evaluating ways to meet this market need, two events occurred to provide the solution. First, one of its suppliers asked if it needed a single-board, single-slot computer with a fast Ethernet port on it. Second, NT Embedded was announced.
In the wake of those two events, it occurred to Bus-Tech developers that they could combine the single-board computer, NT Embedded and their Escon adapter to build an Escon-to-TCP/IP controller in no time. Soon after, Bus-Tech joined the beta program for the new Windows.
The company had already built software for Windows NT Server that would pass TCP/IP traffic between the network and the mainframe. Bus-Tech engineers were able to move the company's existing application into NT Embedded with only minor changes.
The longest part of the development cycle was the hardware verification testing. Bus-Tech wanted its mainframe appliance to be as close to plug-and-play technology as possible. It integrated the one-slot single-board computer, a Pentium processor and an Ethernet chip into a box about the size of a pizza box with one slot for the adapter and a fast Ethernet RJ 45 connection.
Bus-Tech plugs its PCI channel adapter into that one slot for connection to an IBM Escon channel. The appliance supports the IBM mainframe at up to 17 Mbytes/second and runs at 80 percent to 90 percent capacity.
The adapters, full-length ones with an Intel 960 processor on them, are much more complex than a typical Ethernet adapter; integrating them into new platforms requires rigorous testing. Company engineers were able to begin the thorough test cycles early, since they could start testing within a week of receiving NT Embedded Release Candidate 1.
Bus-Tech conducted lengthy tests, which ran between 10 Mbytes/s and 12 Mbytes/s through the channel connections for an entire weekend.
The whole development process took about four months-in March, the company was ready to deliver the product in June. But it had to wait until August, when NT Embedded was released.
Bus-Tech chose NT Embedded for a couple of key reasons. First, the developers didn't want a keyboard, monitor or mouse on the unit. Because the mainframe appliance uses a commercially available single-board computer, a video port and a keyboard port are exposed on the back of the box. The operating system has null drivers for keyboard and mouse, making it easy to inactivate them. That makes it impossible for anything in the system to be activated if a monitor or keyboard is plugged in. Second, because the developers didn't want the noise or potential failure associated with having a hard disk in the system, they used a spindleless solid-state memory device instead of a hard drive.
The challenge was to fit both the NT Embedded Runtime operating system and the application software on an 80-Mbyte solid-state memory device. The NT Embedded portion of the application is approximately 60 Mbytes to 63 Mbytes. And the whole solution, including the Bus-Tech drivers, is approximately 65 Mbytes.
Operating system size was controlled with Target Designer, included in NT Embedded. The design aid allowed designers to drop out all the programs that weren't needed for a communications controller, such as the utilities, Notepad, the clock, the calculator and even the help files. The mainframe appliance is a streamlined Windows NT-based system with a TCP/IP stack, customized drivers and services for administration.
Bus-Tech created its own TCP/IP protocol-called TCP/IP Pass-through-for moving the traffic between the LAN and the mainframe. However, the mainframe appliance uses the Microsoft TCP/IP stack for NetMeeting conferencing software, which is used to administer and configure the box. The six-foot crossover cable included with Bus-Tech's mainframe appliance enables administrators to plug a notebook computer directly into the back of the box and use NetMeeting and TCP/IP to troubleshoot and configure.
When they connect, administrators get a Windows NT Explorer-type window that includes only the icons needed for administration. Administrators can change the IP address that's used for NetMeeting administration so that they can put the machine on their network and administer it remotely.
Once the IBM mainframe computer is configured and ready for the device, which requires a reload of the mainframe, a customer can have the mainframe appliance running in about 15 minutes, making the system close to a plug-and-play peripheral.
Windows NT Embedded and its Target Designer feature enable Bus-Tech to quickly and cost-effectively customize the operating system it uses to the application it is building.
The developers were able to remove all the extraneous files and services in the operating system. Using Target Designer, they were able to check dependencies to make sure that components required to make the system run were not deleted. Bus-Tech used null video, keyboard and mouse drivers so that the system will run without those components while supporting remote configuration.
By using NT Embedded, Bus-Tech was able to scale down the operating system to just the components necessary to support its mainframe appliance for networking. It saved on development time and enabled Bus-Tech to build a headless system. The process allowed the company to fill a gap in its product line and port its existing application to a new, commercially available hardware platform for about 40 percent less than the cost of developing a proprietary product. n
PATTY MCKEEHAN, A MEMBER OF PRODUCT MANAGEMENT FOR WINDOWS NT EMBEDDED AT MICROSOFT CORP., ALSO CONTRIBUTED TO THIS REPORT.