The
Bernoulli Box:
A Low Cost Alternative to Sharing
Data in Limited Environments
A
Bernoulli Box is a removable
hard disk cartridge storage
device or to put it another
way, diskette drives that accommodate
10 or 20 megabyte cartridge
diskettes. The two advertised
and perceived uses of a Bernoulli
subsystem are that it provides
a single PC with a virtually
unlimited amount of hard disk
storage space, and functions
as a backup system that generates
‘working’ copies.
This technology has been applied
in a way that allows many PCs
to use a single Bernoulli Box
for conventional applications
as well as creating access to
a common hard disk storage device.
Case Study
A client had a three-terminal,
40 megabyte, Apple III/Corvus
Network. They had run out of
hard disk space and a consultant
had recommended the purchase
of an 80 Megabyte hard disk
as a solution to its problems.
Since the system was old, unreliable
and could not run IBM based
software, a Requirements Analysis
was performed to determine the
cost to address its data processing
needs in an MS-DOS environment.
Interviews with staff and management
revealed that this firm performed
three data processing functions:
Word Processing
Electronic Spreadsheet
Write-up Work
All of these functions needed
to be performed by three support
staff at separate locations.
The word processing and spreadsheet
functions did not require the
sharing of data. However, account
write-up work was to be expanded,
and management wanted each staff
person to be able to perform
write-up work on any of their
accounts.
Initially, a Local Area Network
(LAN) was explored. However,
the estimated cost of the network
exceeded the amount of the client’s
budget for a system. So the
problem posed by this engagement
became: How can the three users
have access to the same data
source without incurring the
cost of the Local Area Network?
Further inquiries regarding
the way in which each user needed
to share the common data source
revealed the following characteristics:
No user needed to access the
same account at the same time.
The deadlines for the accounts
were at different times during
the month.
Because of the many staff duties,
the timing of access to the
shared data source was flexible.
With this information, the requirement
of sharing a common data source
took on a new look. The shared
data source did not have to
be available to multiple users
at the same time, but only distinct
single users at different times.
The Bernoulli Box, in its traditional
role, met all the needs of this
client in a single user mode.
Increased Hard Disk Space
The client was expanding his
account base which would increase
hard disk requirements substantially.
With the Bernoulli Box, the
client would have infinite hard
disk capacity and could very
economically increase hard disk
space by purchasing additional
cartridges.
Data Security, Backup
The Bernoulli Box offered backup and disk storage features that were particularly attractive to this client:
The ability to store systems of different
accounts on separate cartridges was a desired security feature.
If one cartridge went bad, it only affected one account.
This would not be the case on a conventional hard disk.
The ability to have a ‘working copy’ as a backup was attractive
to the client because of its immediate usability.
The fact that there were two cartridge diskette drives provided additional security. If one of the cartridge diskette drives became damaged, the other drive could be used while the damaged one was out for repair. This would not be possible with a conventional hard disk.
The only requirement not addressed by the use of a Bernoulli Box was the access by multiple users. This requirement was met by attaching the Bernoulli Box to a three-station switching device, purchasing Bernoulli Box control cards for each of the three computers, and connecting the new computers to the switching device. With this configuration, each one of the PCs could have access to the Bernoulli Box – but only one at a time. A user desiring access only needed to switch their channel, insert a hard disk cartridge, and type “D:”
The client was pleased with this alternative because it addressed all of its data sharing needs without excessive additional cost.
A Local Area Network is preferable when the sharing of a common data source is needed. But in a situation where the cost of a network is prohibitive and the sharing of requirements are limited, the un-traditional application of removable hard disk technology provided the client with an acceptable alternative.
The microcomputer industry is changing at a phenomenal rate. Advancements in technology are constantly providing us with new alternatives to managing client’s data processing needs. Sometimes, the correct solution for our client lies not in that new technology, but rather in proven technology applied in a unique way.
Published in The CPA Journal, March 1988, pp. 68-69.