| The IBM System/7 was introduced to the world 35 years
ago as a rugged and highly reliable computer that could
measure, test, analyze and control industrial and laboratory
events as they occurred. The sensor-based system, which
rented for as little as $352 a month, was IBM's lowest-cost
computer at the start of the 1970s.
It was designed to provide a modular approach to sensor-based
data processing applications for the stand-alone user
(with a system dedicated to a single application) as
well as the complex system user (with several IBM computers
interconnected in a plant- or company-wide network).
The IBM System/7 was made up of a processor module
(the IBM 5010), input/output modules (the IBM 5012 multifunction
module, IBM 5013 digital input/output module, IBM 5014
analog input module and IBM 5022 disk storage module),
and an operator station (IBM 5028). The processor module
and from one to 11 input/output modules were housed
in enclosures (IBM 5026) that also provided internal
power supplies, signal distribution, and an operator
console.
The system's growth could be achieved easily by adding
input/output modules to expand sensor attachment capability,
and the computer's all-monolithic memory could also
be expanded on site.
A host computer attachment allowed the System/7 to
operate with an IBM
1130, an IBM 1800, most models of the IBM System/360
or an IBM System/370 for additional input/put and computational
capability.
The System/7 had a main memory made entirely of monolithic
circuits, which contributed greatly to the system's
compactness, reliability and high internal speeds.
To store data and instructions, the computer used silicon
chips rather than the magnetic cores that were the convention
at the time. Those chips measured less than one-eighth
of an inch square and contained 1,434 microscopic elements.
Logic circuits in the system were also monolithic, making
possible switching speeds from eight to 12 nanoseconds
(billionths of a second).
Numerous remotely located sensing devices -- such as
gauges and instruments which recorded changes in temperature,
humidity, pressure or flow -- could be attached directly
to the System/7. As many as a quarter-million readings
per second could be recorded and analyzed almost instantaneously
by the system. The computer could then generate signals
required to control the equipment used in manufacturing
and laboratory processes.
The low-cost System/7 provided unattended continuous
process control in industrial plants and other rugged
environments.
Input such as temperature variations, hygrometer readings
and fluctuations in pressure were termed analog data.
The System/7 measured those analog quantities and converted
them into computer-compatible form (binary numbers).
The computer then generated the proper signals to control
the equipment, e.g., turn on a switch or adjust a valve.
In the System/7, the IBM 5014 analog input module was
available in two versions, one with scan speeds of up
to 200 points per second; the other operating at scan
speeds up to 20,000 points per second.
The IBM 5012 multi-function module provided analog
input/output, digital input/output with process interrupt,
and control devices of the IBM 2790 data communication
system. (The interrupt feature meant that the system's
processor could be programmed to accept and respond
to priority instructions. For example, should the signals
from a gauge indicate a danger point, the system would
interrupt what it was doing, send a signal to remedy
the condition, and then return to its program.)
The operator station
consisted of a typewriter-like keyboard and request
key, printer, paper tape reader and paper tape punch.
Operation of those devices was under program control.
Push button switches disconnected the station from the
system and permitted it to be used as a source program
preparation device.
Two methods of preparing programs for the System/7
were provided by MSP/7, a set of modular systems programs.
The set included the IBM System/7 Assembler, which loaded
into the computer via the paper tape, and allowed the
user to write programs at the operator station.
The second method was called Host Preparation Facility
and included a library of sensor-based subroutines that
a larger IBM computer could use to prepare programs
for the System/7.
A new disk module -- the IBM
5022 disk storage module -- was rolled out
in July 1971 to significantly enhance the storage
capacity and flexibility of the System/7. And two years
after that, the company launched a new, larger-capacity
model of the System/7, along with enhanced communications
and stand-alone programming capabilities, which together
broadened the scope of the system's sensor-based applications.
The new model's significantly expanded memory of up
to 65,536 words could allow users in a wide range of
industries to run either several small applications
or a single large one without the need for a host computer.
Computer historian Emerson Pugh and his co-authors
wrote of the System/7 that:
"the new product was off to a slow start
until its reception was improved with the aid of tangible
applications and demonstrations. Applications served
in addition to industrial process control included the
monitoring of water and air pollution, hospital patients,
vehicular traffic, badge-lock door entry, telephone
tolls, laboratory experiments, and energy conservation
in buildings. The dependence on host computers was reduced
in a new model introduced in 1973.
Design engineers involved have said that "the
system ultimately was successful, but in areas not entirely
anticipated by its designers, and, as intended, mostly
in areas other than process control. In retrospect,
it was an expensive machine, ahead of its time in orientation
to host support and hierarchical interconnection, which
often was at a disadvantage when compared to less sophisticated,
stand-alone minicomputers."*
To learn more about this interesting computer, a visit
the System/7 Reference
Room will start you on your way.
* IBM's 360 and Early 370 Systems. Emerson
W. Pugh, Lyle R. Johnson and John H. Palmer. (Cambridge,
Mass.: The MIT Press, 1991), pp. 586-7. |
