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May 1990

The right programming language facilitates equipment upgrade.

by Hoffberg, Alan M.

    Abstract- A case study of the accounting department of an actual company is used to demonstrate the best method for upgrading electronic data processing equipment and software. The careful choosing of computer hardware and software can make upgrading a system a simple process instead of a complicated and tedious task.

Careful selection of programming languages, application software, and computer operating systems can make subsequent upgrades of a system a dream-come-true rather than a nightmare. The following real-life case illustrates an example of how one firm moved from a single user microcomputer to a multi-user minicomputer and avoided both reprogramming and performing parallel testing for a lengthy period.


The scrambling of satellite television signals built to a crescendo in the spring of 1986. Up to that time, owners of home television receive- only (HTVRO) satellite dishes simply dismissed the advance warnings from the cable television industry about the coming of wide-spread scrambling . . . similar to ignoring one who carries a placard announcing the "end of the world is coming." The arrival of scrambling triggered an avalanche of subscriptions for unscrambling equipment and capabilities, and created a new industry. The client, XYZ, quickly reacted to create a new business: selling wholesale HTVRO subscriptions to cable TV operators across the U.S.

Due to signal scrambling, owners of satellite dishes could no longer receive programming from XYZ . . . unless they bought a subscription to unscramble the signals. Although dish owners might purchase their subscriptions directly through a nationwide toll-free telephone number, thousands of dish owners subscribed throught their local cable TV operators.

Billing and Accounts

Receivable System Installed

on a PC

In the weeks that followed the initial scrambling, one group at XYZ drafted an HTVRO subscription license policy as a foundation for direct sales by the cable operators, while the accounting department focused on its assignment to design and implement a billing and accounts receivable system. Preliminary drats of the license policy were used to determine the billing formula and format. Then decisions had to be made concerning the acquisition of hardware and software. Since no one could make an accurate guess as to how this new business might grow in the months ahead, XYZ wanted to install and implement the system on a PC-DOS or MS-DOS based personal computer, since XYZ was already using these in the accounting department. On the other hand, the transaction volume could grow beyond XYZ's PC capability as this new business developed, requiring a multi-user system in the near future.

To further complicate matters, even though a significant portion of XYZ's staff used PCs and mainframe computer terminals in their daily work, there existed no local XYZ computer support staff, so the new system had to be user friendly. Furthermore, it was determined that the system had to include the database characteristic of a file dictionary, so authorized users could access files by using a query oriented language for the purpose of preparing ad hoc reports. Finally, the system design had to be flexible to accommodate evolution of the HTVRO industry, so that enhancements and changes could be made to the system with minor effort.

Revelation, TM an implementation of the PICK Operating System TM was selected. Revelation operates on MS-DOS or PC-DOS based PCs. It supports database dictionaries, query language, and the PICK BASIC application language, which accesses both the database dictionaries and operating system commands. It performs like its counterpart on a microcomputer, and offers capability of being ported over to a minicomputer, in case the need ever arises. It was determined that the system had to include special look-up and cross-reference features to facilitate human interaction with the computer application. Even though the system did not require all capabilities at the time, it was anticipated that other XYZ departments would eventually need access to the wealth of data the system would maintain. An automatic data validation was included in the software design, to prevent incorrect information from getting into the database.

Time to Test

After a month of developing and testing, menus and file maintenance screens were installed on one of XYZ's PCs. Personnel were then trained to use the file maintenance programs. The XYZ staff immediately began the task of entering data from hundreds of registration forms that had arrived by mail from cable operators across the nation.

By this time, the HTVRO industry was beginning to accelerate.

In the weeks that followed, the database of wholesale subscriptions began to grow, and subscription count reports began to trickle in from cable operations. The final version of the billing and invoicing software was implemented, and the system went live.

The transaction volume was not more than a few hundred at this point. The staff performed a 100% verification of the system reports for the purpose of running parallel and identifying errors in the design and data. Design problems were immediately corrected, data reconstructed and reports rerun as required, until everyone was satisfied with the results. However, the computer began rejecting transactions that otherwise looked correct.

Upon researching the problem, it was discovered that various departments within the compay maintained their own database systems without cross-checking the data between systems. Because the new system integrated all of this information, the checks and balances included in the system design detected problems that no one realized existed. The various departments corrected their information, and the revised data was input, recalculated, reprinted, and the invoices sent out. The system was officially live.

After several months, the HTVRO database grew to a number of megabytes on the PC. Furthermore, XYZ needed an accounts receivable system to integrate with the HTVRO application. It became increasingly difficult to manually maintain the receivable records. Rather than reinvent the wheel, XYZ licensed a well-known accounts receivable system for the PICK Operating System. Although the licenser neither designed nor marketed the application for use on a PC, we did not see that as a deterrent to implementing it on XYZ's PC (with the perspective that XYZ would "someday" install a minicomputer). Software was developed that provided the capability of transferring files of unlimited size between the micro- and minicomputer systems.

During the next six months, the transaction volume continued to grow. The PC became disk and processor bound. An accelerator board was installed, increasing execution speed by about 500%, since Revelation uses virtual memory and mainframe demand paging concepts. This helped for a few months. However, the wholesale subscriber base continued to grow to about one thousand, and the number of individual subscribers grew by tens of thousands. More than one person needed to have simultaneous access to the HTVRO application in order to maintain the data. We began thinking about upgrading to a minicomputer for this and other database applications.

Minicomputer Was Ordered

XYZ ordered an entry level McDonnell Douglas 6000 series minicomputer, which XYZ could later upgrade in speed, storage capacity, and number of users, as its needs materialized. The new system supported Reality, TM an advanced version of the PICK Operating System. The initial hardware configuration included eight serial ports. XYZ assigned one port to a printer, another to a modem, and the remaining six to CRTs in various ofices on the same floor, using a proprietary local area network (PLAN) technology.

As part of the original implementation strategy, we planned to operate the new minicomputer system in parallel with the PC for one month. As the installation and implementation proceeded, however, this strategy changed.

The System Was Operational

By Noon

We immediately transferred all of the Revelation programs and data files from the PC to the minicomputer over a 2400 baud modem link taking advantage of the link's built-in data compression and error correction. We then re-compiled the programs under Reality. The system became operational by lunch time. The next day, after reviewing the sample reports, we made the decision to immediately go live with the new hardware, and forego the parallel testing period. We felt confident in the new system because all of the data and programs were identical to those on the PC-based system.

Over several months, as the system requirements continued to evolve on the minicomputer, we developed new applications on the firm's PCs using Revelation. After completing the design and testing, we uploaded the software by telephone to XYZ's minicomputer. We then re-compiled the software and placed the software into production mode.

Following the successful implementation of the HTVRO system, XYZ added other applications, increased the number of ports to 16, added a modem rack and three more modems, added a 300 line per minute printer, installed a one-half inch magnetic tape drive to interface with the mainframe computer, and installed telecommunications in its regional offices across the U.S. to provide access to the database on the minicomputer.

Looking back, in 1987 XYZ's Management Information Systems (MIS) division announced it wanted to consolidate the above applications on its centralized mainframe computer. Even though it is now 1990, XYZ continue to use the above system daily, and XYZ's MIS group continues to reaffirm its commitment to replace the minicomputer, although it has not announced any specific target date.

McDonnell Dougls recently introduced its Model 14/100 peripheral card which plugs into any available 8-bit slot on either an 80286 or 80386 based machine, and makes it possible to interchange object code as well as magnetic tape between its minicomputers and any microcomputer, without the need to re-complie the program source code. The 14/100 also turns the microcomputer into a true nine-user contained on McDonnell's complete line of minicomputers. Had this peripheral been available in 1986, XYZ could have used it as a major justification for pursuing the path that it did.

In summary, this case illustrates how a small department in a large national firm carefully planned and implemented a long range plan even though senior management wanted a short term "inexpensive" solution. By establishing a proper foundation, this firm's accounting department easily migrated to more capable hardware as its needs evolved without the usual headaches and expenses of redesigning the applications, reprogramming, testing, conversion, and retaining.

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