Texas Instruments' Cal-Tech Handheld Calculator Prototype
Image Courtesy of Texas Instruments
Used with Permission
This is a photo of one of very few Texas Instruments(TI) "Cal-Tech"
proof-of-concept battery-powered printing electronic calculators produced.
The Cal-Tech was an internal TI project to develop advanced integrated
circuit technology for application in what could potentially become a
consumer product. Prior to the development of the desktop electronic
calculator, integrated circuits were only used in commercial computers,
military/national security systems and spacecraft(manned & un-manned)
electronics.
The idea of using digital integrated circuit technology in consumer-market
products could potentially open up a floodgate of opportunities for sales
of advanced ICs. The problem at
hand was figuring out just what kind of device could address the consumer
market that would need the complexity of digital integrated circuits yet still
be affordable enough for the market.
Television and radio manufacturing companies had begun to look into the use of analog
integrated circuits to reduce the component count and complexity (as well as
cost), but the only product using digital logic that existed at
the time that was was the desktop electronic calculator, which was mainly marketed
to mid-sized to large business, financial and scientific enterprises due to the
fairly high price tag for the machines. The integrated circuit technology used
in existing IC-based calculators was not of sufficient circuit density to gain the economies
of scale that the use of large-scale (LSI) integrated circuits could provide. Fewer ICs with
much more logic packed into each chip could bring down the cost of implementation of a calculator
to the point where such a machine could be viable as a consumer product.
The proof-of-concept project at TI's Semiconductor R&D Laboratory got its
start in 1965 at the direction of TI's president,
Patrick E. Haggerty(3/17/1914-10/1/1980). Haggerty and one of
TI's engineers, Jerry Merryman(6/17/1932-2/27/2019), happened to be on a plane flight together.
During the flight, they they chatted about the possible uses of advanced
integrated circuits in the consumer marketplace. The result of the
discussion was an idea for a pocketable, battery-powered electronic
calculator that was low-priced enough for the consumer market. The thought
was that this could create a huge demand for advanced digital IC's for
calculators, and Texas Instruments could be poised to fill that demand.
As a result of the discussion, Haggerty decided to fund a proof-of-concept
project to develop the technology to produce such a calculator. The
project got its start in 1965 at Texas Instruments' Dallas, TX, Semiconductor
Research & Development Lab. Haggerty appointed three key members of a
small team dedicated to the development of the calculator. The leader
of the team was
Jack Kilby(11/8/1923-6/20/2005), one of
the original inventors of the first integrated circuit. Along with Kilby were
Jerry Merryman, and
James Van Tassel(2/15/1929-6/19/2018). The three men quickly blended their skills and developed a
rapport that generated progress at a surprisingly rapid pace.
The team began the development of the logic design, building a breadboard version of the
logic for the calculator using TI's off-the-shelf small-scale digital
integrated circuits so that the design could be wrung
out before committing the logic to large-scale integrated
circuits. Once this large prototype (consuming
two stacked layers of hand-wired breadboard circuits placed on large
sheets of plywood laid over three large tables) was working properly, the process to reduce all of this
logic down to a small number of complex digital ICs began.
The first-article Cal-Tech became operational in December of 1966, using
four large-scale bipolar discretionary-wired gate-array integrated circuit
devices that were a serious leap forward in IC technology. The calculator was completely
self-contained, with a rechargeable battery pack included. The only exterior
part was a small power-pack that would serve to run the calculator on AC
power, as well as for charging the internal battery. TI's choice of bipolar
technology was unusual in that there were limits to the complexity of
bipolar ICs as opposed to the up-and-coming Metal Oxide Semiconductor
(MOS) technology that made it possible to create much smaller and less
complicated transistors than those implemented using bipolar technology.
TI's expertise was with bipolar IC technology - they had not yet
invested deeply in MOS devices, leading to the bipolar large-scale devices
being the choice for use in Cal-Tech.
The logic of the calculator breadboard was implemented in the gate-array
chips, which provided a large number of standardized logic elements arranged on the chip
such that a layer of metalization could be deposited on top of the array
of logic elements that connected them together to create the logic
of the calculator. The calculator used four of these gate-array
devices, as well as three 24-bit bipolar shift-register integrated circuits
that were used for storing the calculator's working registers. The Cal-Tech used
a new thermal printer technology developed by Texas Instruments for data
logging equipment. The thermal printer printed out the inputs and results of
calculations by energizing tiny heating elements on a ceramic substrate
that would form the image of the digits and symbols as darkened dots on a narrow strip of
special thermally-sensitive paper that was
manufactured for TI by 3M (Minnesota Mining & Manufacturing).
In the end, Texas Instruments' management team did not support Haggerty's
proposal of the company entering the rapidly-changing electronic calculator
market itself, but was very interested in partnering with
an existing calculator company to develop a commercially-viable version
of the Cal-Tech. Cal-Tech itself was simply too expensive to make to be
a practical product, but it did prove that Texas Instruments had the skills
and technology needed to develop such a device to the point where it could be
further developed into a consumer product.
A small number of calculator companies were shown the
Cal-Tech. Amongst them was Canon, a Japanese company that was already a large customer
of TI's small and medium-scale off-the-shelf integrated circuit technology
for its early IC-based desktop calculators (an example being the
Canon 141). When
shown the Cal-Tech, Canon's executives and engineers expressed a strong
interest in developing a calculator like Cal-Tech for production as
a consumer product. A partnership was quickly put together for joint
development of such a calculator, which became a product in the
Canon Pocketronic.
The Pocketronic calculator, which ended up a bit longer, but not quite
as wide as the Cal-Tech, and was about the same thickness as the Cal-Tech,
and weighed a little less because of the use of a plastic cabinet versus
the metal cabinet of Cal-Tech. The Pocketronic became available for sale
in Japan in the fall of 1970, and in the US(at an MSRP of $400) in early 1971. The machine
was "pocket-able", but you needed a pretty good-sized pocket to hold it,
though it would fit comfortably in an average executive briefcase, leaving
plenty of room for other normal briefcase content.
The Canon Pocketronic was a direct descendent of the Cal-Tech, but was based
on MOS integrated circuits developed by TI rather than the bipolar chips used in Cal-Tech.
Texas Instruments had quickly developed its MOS integrated circuit technology after it was realized
that it was simply too costly to implement the complex logic required
for devices like electronic calculators using bipolar chip technology as was
used in the Cal-Tech. The Pocketronic proved to be a successful product
for Canon, with the calculator becoming coveted by high-end executives
as a "show-off" item, as well as being a useful tool for on-the-go calculating.
The chips that TI developed for
the Pocketronic were TI's first electronic calculator chip-set, and set the
stage for TI's eventual development of its first calculator-on-a-chip,
which TI ended up using to produce its own electronic calculators for
sale under the Texas Instruments brand, as well as selling the chips to calculator manufacturers
for use in their own calculators. The vision of Pat Haggerty had proven itself, as Texas Instruments
is one of very few US calculator makers that are still in business to this day.
The very first Cal-Tech calculator was presented to Haggerty in March
of 1967 as a memento of the development of the machine. When Haggerty left
TI to go to work for National Cash Register(NCR), he left the calculator in the care of
Texas Instruments, which later gifted the machine to the
Smithsonian's American Museum of Natural History, Kenneth E. Behring
Center. The Cal-Tech is exhibited in the museum's
permanent collection.
For more information, see the Old Calculator Museum's exhibit for the
Canon Pocketronic.
