From Telecomputing Magazine

PCBoard Fosters Multiple Nodes
By Vince Juaristi

In a world of lap tops and burgeoning mainframes, bulletin board systems have
grown in popularity and carved their own deeply rooted niche.  With this
apparent rampage, users are finding new and innovative resources to improve
system response times, reduce equipment necessities, and expand system
useability.

Normally, user capabilities are simply limited to software efficiency, speed,
and reliability.  Few programs in the past have produced sufficient
telecomputing options, but not anymore.

Since the recent release of PCBoard 14.5, users both large and small have
chicanerously enhanced their systems to accommodate several nodes and augment
system speed.

At Word Perfect Corporation, for example, Dave Smith, a technical service
representative, maintains a PCBoard user base in excess of 28,000 users. The
system holds information about each registered copy of Word Perfect and acts as
an enormous database for the company.

Each day, Smith intently studies his system that is nothing short of
extraordinary, if not by its shear size, at least by its use of Cubix slave
cards.

The Word Perfect network utilizes PCBoard on a Novell system.  It is comprised
of three standard machines and 28 Cubix slave cards that ultimately create 31
nodes.

Each Cubix card includes two 12 MHz AT processors and 1 Megabyte of Random
Access Memory (RAM).  The cards are enclosed in chassis cases and a controller
board is inserted in the file server.

Since each card operates a unique microprocessor, the Word Perfect system does
not suffer from speed degradation.  In fact, using Zmodem protocol, file
transfers have averaged over 1,600 characters per second.

Unlike Word Perfect's network, however, large systems that are condensed to only
a handful of physical machines often suffer from reduced speed and memory
shortages.  Of course, these shortcomings do not normally occur while using
slave cards, but rather when a user employs multitasking software.

Andrew Bilski, a Polish resident of Bethesda, Maryland and newly sworn citizen
of the United States, runs the Main Frame BBS with DESQview.  His five node
system operates inside one machine which he cleverly modified to handle
additional communication ports and interrupts.  As he says with a particularly
noble accent, "When I type WHO [PCBoard command] and see five nodes active on
one machine, I think it's great."

To allow communication through a COM port, the microprocessor must be
interrupted and instructed to send or receive information.  As a result, each
COM port requires a unique interrupt to function properly.  Bilski, to
accommodate his needs, has borrowed two interrupts from alternate hardware
unused by his machine.

Like Word Perfect's slave card system, Bilski utilizes less equipment and
therefore softens the blow to his pocketbook.  "With DESQview," says Bilski,
"there's no extra computers, no tables, no networking, no monitors or
keyboards."

At first, a multitasking structure seems to be a panacea for system operators
with limited financial resources who want additional modem lines. However, with
each additional line, speed degeneration occurs which makes, as Bilski says,
"16550 UART's pretty much mandatory."

The UART chip includes a buffer that allows the microprocessor, while
multitasking, to keep pace with 115,200 baud.

Of course, since one computer operates several lines, all are affected if the
computer malfunctions. This inevitably is an unfortunate disadvantage.

For Bilski, though, the centralized location of all his nodes could not be more
advantageous.  As he says, "Since DESQview matured and PCBoard matured, the
results are simply amazing."

No doubt, PCBoard's maturity has improved systems throughout the world, but like
all things, the greatest advancements flow surreptitiously from clever minds.

Copyright 1991, Telecomputing Magazine -- All rights reserved.