The economic advantage of small multi-user Unix systems over LAN-based computing has led to their proliferation, especially in replicated sites, with applications such as point-of-sale, airline terminals, small business administration and self-serve gas station control, to name a few. These devices are normally in the serial interface, due to low cost of cabling and ease of maintaining. One factor drawing users to Unix is the low investment cost, a result of keen competition. Also, Unix takes advantage of multitasking in high security open systems more cost-effectively.
This is particularly true for retail, hotel, manufacturing, distribution, hospital and banking applications. Although the PC connectivity industry has been well established for some years, the serial connectivity is continuing to grow— particularly in the areas of direct connect, server/LAN, distributed connectivity and wide-area network (WAN) communications. Devices that users need to connect include terminals, modems, printers, POS terminals, DOS PC, and the like.
Need for connectivity
The development of OS/2, NetWare and NT networks, has brought about a need for connectivity solutions for serial devices such as printers and modems that are attached to the servers on a LAN.
Today’s PCs have become immensely powerful with the advent of 486 and Pentium processors and the ability to have multiple processors in one single system to increase performance. Coupled with ‘shrink-wrapped’ Unix operating system software, these servers are fuelling the downsizing trend. In many cases they have more processing power than some mainframes.
To achieve and support hundreds of users connected via terminals, these PC-based Unix servers start exploring the use of cluster controllers, a specialised front-end computer for controlling distributed groups of serial devices beyond the immediate vicinity of the server. Workgroup functionality and central control and monitoring are important for such a solution. For example, Stallion’s Easyreach product, which alone supports over 2,000 serial devices, transparently provides both local (within a building or campus) and remote users (in branch offices) connectivity to a Unix server.
The advantages of server/LAN-based serial connectivity, such as access to multiple hosts, better resource sharing and the ability to locate serial devices anywhere on the network has also led to substantial growth in this segment.
Originally the domain of LAT-based DEC systems, TCP/IP-based Unix LANs are now popular in multisystem installations. Many terminal servers are available for users of such LANs, but not many are designed to harness the functionality of Unix networks.
Entry-level Unix solution
Frequently, a user may need to connect a small user group (eight or more and normally using low-cost terminals) performing some simple functions like inputing data or controlling industrial equipment.
Ideally any new or extended group can be connected directly to the host and become transparent, so that information is available instantly. Installing a PC-base LAN is not feasible and costly. Under such circumstances, investing in a Unix host and using serial connections will be practical and cost-effective.
Graphical interface and system management
Investing in low-cost Unix solutions used to mean sacrificing user-friendlines. Also, troubleshooting was more difficult. [In a PC environment, it can be easily done using utilities such as those from Norton. Unix system management, however,
was by character management and was frequently left to 'experts', with the result that it is usually costly and time consuming]. This was true a few years ago, but now, vendors have started to incorporate user-friendly and graphical base system management tools for Unix system tuning and performance analysis. PC LANs may be becoming more popular, but low-cost Unix solutions, with their increasing ease of use, low entry cost, and the ability to take advantage of open, multitasking and multi-user functionalities, are still worth a second look.