The Evolution of Today's Calculator
by Robert King
Reprinted from the Spring 1997 issue of The International Calculator Collector.
(Editor's note: The following article highlighting the seven major developments leading to today's calculators was written by Robert King, an IACC member and avid calculator collector since November 1994. He is the state archaeologist for the U.S. government's Bureau of Land Management in Alaska. Robert approaches calculators as a modern artifact, providing not only a unique way of looking at these marvelous inventions and their history, but also some great insights and information about our recent culture.)
If you think about it, today's calculators are marvelous achievements. Many of us old enough to remember the 1960's and 1970's still recall the thrill of seeing and then owning one of these amazing devices. For us, it was owning a piece of the future, especially when we realize that these wonderful machines weren't even around when the first men landed on the moon in 1969!
Yet, like all other inventions, their development came in stages -- and a useful way to look at their fascinating history is in terms of "evolutionary" or "achievement" milestones.
In this regard I see that there are seven such "milestones" leading to today's commonly-used calculator. They are: #1 portability, #2 small size, #3 replaceable batteries, #4 increased functions, #5 liquid crystal display (LCD), #6 solar power, and #7 cheapness. To follow is a brief look at when each of these achievements first appeared.
The first electronic calculators appeared in the 1960's as large desk-top electric models. During this decade, they passed through three stages before achieving real portability. First, the earliest ones in the early 1960's used transistors.
Next, combination transistorized models appeared incorporating a few relatively primitive Integrated Circuits (ICs), and lastly units were introduced with just ICs. What was happening at this time was that the IC, itself, was evolving and becoming more and more powerful requiring fewer and fewer to drive a calculator.
By the later 1960's, a small number of IC's only could substitute for what a few years earlier required dozens of transistors. This meant that the size of a calculator could be correspondingly down-sized.
By the late 1960's, it became possible to pack all the components for a four-function calculator into a unit less than the size of an average shoe box. At this point, reasonable "portability" was achieved.
Important early examples include Sharp's all-electric QT-8, introduced in late 1969 to early 1970, followed in mid-1970 by their similar rechargeable model, the QT-8B. Also, Sanyo's pioneer ICC series of portable models (e.g. ICC-0081) and a few others like the Dictaphone 1680, were equally notable during this early period.
#2 Pocket Size
The push toward smaller and smaller calculators didn't stop at mere portability. As we know, some calculators today, like watches, are so small that they are almost too tiny to be used easily by our big (and sometimes clumsy) fingers. But that's getting ahead of the story.
The real milestone was achieved when calculators became small enough to be carried in your pocket -- and here I mean an average shirt pocket instead of an oversize coat pocket. Following Sharp's and other companies' pioneer portable models, the race for smaller size was a swift one.
A major push toward pocket sized models came in 1970-71, when at last all the calculating components for a four-function calculator could be packed on a single IC. That was, and remains, the real key toward creating today's ever-smaller and more sophisticated units. During 1971, Bowmar's 901B and especially Busicom's Handy LE-120A, plus a few others, achieved true shirt-pocket size.
#3 Replaceable Batteries
The use of replaceable batteries in the earliest portable calculators was certainly an idea in the minds of the engineers of the later 1960's designing ever-smaller units, yet there was a problem to overcome. Calculators at this time used only the earlier (non-LCD) types of displays which required a lot of power. Thus, they would quickly drain batteries, making AC power or rechargeable batteries the more economical choices, albeit less convenient.
In part to solve this problem, engineers further pushed the development of LCD technology for calculator displays as a way of cutting power needs of calculators. Consequently, replaceable batteries lasted much longer and calculators using them gained the upper hand for reasons of economy and convenience. No longer would people need to frequently plug-in for recharges or constantly buy quickly-drained replaceable batteries.
Yet in the developmental stages leading to the adoption of replaceable batteries, there were interesting developments which will be briefly traced.
Going back to the earlier units, Sharp's earliest portable unit from late 1969 to early 1970, the QT-8, was electric. It was soon followed in mid-1970 by the QT-8B with rechargeable batteries. Interestingly, this latter machine's charger was a virtual docking unit where the calculator clamped into a charging cradle.
By late 1970 to early 1971, this was reduced for Sharp's EL-8 which used a simpler AC adapter that plugged into the calculator, basically foreshadowing adapters of the later 1970's.
The initial introduction of replaceable batteries also happened in 1971 on portable, and indeed pocket-size, models. Busicom's Handy LE-120A, a Light-Emitting Diode (LED) display model, was a pioneer in this development. Yet due to the power situation mentioned earlier, they did not catch on as practical LCD models were not yet ready.
Interestingly, there were two short-lived attempts by some companies, including Sinclair, Texas Instruments (TI), and others to "fix' the power-hungry problem on certain LED units. At least one Sinclair model, the Executive, "pulsed" the display, thus not using the batteries constantly to keep the display lit.
Other companies, including TI, had the display go blank requiring the pushing a key to "refresh" (re-light) the display (usually the "D" key). TI's model SR-11 from 1973, for example, interrupted the LED display 15 seconds after the answer appeared, requiring the user to push a key to see it again.
Certain companies including National Semiconductor and Casio worked at reducing their power needs by reducing the number of display digits from eight to six.
While these solutions provided for somewhat longer battery life, several companies worked to incorporate a relatively new technology -- the liquid crystal display (LCD) -- into their calculators. LCD's big benefit was its minimal power requirement. However with few exceptions, it would be several years (mid 1970's) before reliability and manufacturing issues would be resolved enough to see the LCD displays on calculators.
Meanwhile, manufacturers were able to reduce the power needs of their calculators to an "acceptable level" through improvement of their integrated circuits and/or a reduction in the number of ICs needed to run the calculator, as well as a reduction in the power need of the LED and fluorescent tube displays. This would hold them over until LCDs were mature.
#4 Increased Functions
When the first portable calculators were introduced in the late 1960's to early 1970's, they were "four-function" units, meaning they could perform only the four basic mathematical functions of addition, subtraction, multiplication, and division.
Yet by early 1972, Hewlett-Packard was marketing a pocket-size calculator, the HP-35, with scientific features for $395. It had over a dozen special "higher" functions, like log, sine, cosine, arc, exponents, and more. This was an amazing accomplishment and shows how quickly ICs were evolving, being able to pack ever-more functions onto a single chip.
Commodore's Minuteman 1, introduced at the same time for under $200, illustrated the state-of-the-art for most non-scientific calculators in early 1972. It was a four-function unit, though already a movable-decimal switch was added. Otherwise, a few other models by this time were adding a memory or at least a "constant" function.
With HP's stunning achievement, however, the trend was clearly set for more and more features soon to appear even on the "cheaper" units. Within 18 months, single memories were joined by multiple memories and percent keys began appearing. Also a clear key for the last entry became available along with business-oriented functions on specialized calculators, like HP's HP-80.
At the same time, scientific calculators used widely by engineers continued becoming more sophisticated with the HP-65, the world's first programmable pocket calculator, appearing in 1974.
Similarly during the early to mid 1970's, other milestone achievements in calculator development were occurring (as recounted below). Certain companies including Casio and Sharp were leading the introduction of truly remarkable units with all sorts of "bells and whistles" appearing at this time or in the later 1970's, such as date, time, chronographic, alarm, and even biorhythm features! This was again due to continuing IC development resulting in even more powerful "brains" for calculators -- and computers.
Also, it could be argued, that the public of the mid to later 1970's was becoming almost jaded to the rapid evolution of calculators, both wanting -- and expecting -- more new features whether they really used them or not. And for a very few dollars, they got them!
Subsequently, by the mid to late 1970's, pocket calculators were already blurring the lines between being traditional calculators and being small computers (e.g. the HP-65). Today, the distinction is even fuzzier on a variety of relatively inexpensive models.
In all, the point to realize is that by the end of the 1970's, most of the features we are accustomed to today had already appeared and their "evolution" since that time has been much more gradual.
#5 Liquid Crystal Displays (LCD)
Liquid crystals were another invention of the 1960's which, also by the end of the 1970's, became nearly fully developed for pocket calculators. Today, their amazing uses are still to be expanded in other applications, such as in ever-more sophisticated computers, televisions, and other types of electronics. Yet, for calculators, their first commercial use began in the early 1970's. In 1972, a few companies, including Lloyd's, Sears, Harden, and Rapid Data, introduced boxy-looking portable units (all made by Rockwell) with LCD displays lit from behind by a light.
For a very short time, Rockwell even developed and made a smaller version of their LCD calculator using ambient light (sold under the Dataking, Lloyds, Ibico, and Prismatic logos), but reliability issues prevented more.
Concurrently, Texas Instruments tried to develop a LCD version of their first calculator, the Datamath (which used a LED display). The Minimath was also to have been sold in the fall of 1972, but production issues shut down the attempt.
These displays were curious by today's standards -- lighter-colored figures on darker backgrounds (opposite of today's LCD calculators). While gaining some popularity, there were too many engineering and manufacturing problems to immediately adapt this type of LCD technology into the ever-smaller pocket-size units also rapidly developing at the same time.
Indeed these smaller units were able to utilize the older and then-cheaper LED and fluorescent types of displays causing no immediate major rush to adopt and further refine the still relatively primitive LCD technology. Yet some far-sighted engineers understood the long-term advantages of LCD technology -- less power consumption -- and its development continued.
By late 1973, Sharp was marketing calculators with their variation of LCD technology called "Crystal on Substrate" or "Calculate on Substrate" (depending on which Sharp advertisement you read) or COS for short.
Yet it too did not catch on, probably for a combination of economic and engineering reasons. However, Sharp's COS LCDs worked and still work today -- the only commercially sold, early LCD calculators that can claim that.
Subsequently, by 1976-77, what can be termed "nearly-modern" LCD technology was refined enough for use on calculators. Its appearance still differed from today's versions by needing a yellow "screen" or filter to protect the ultraviolet (UV) light sensitive display surface.
While these "yellow-screen" LCD models still used replaceable batteries, the batteries were fewer or smaller (even using miniature "button batteries"). Curiously, Sharp also made a few "yellow screen" LCD models (EL-8024 and EL-8034) that still could use AC adapters, along with replaceable batteries.
By 1978-79, the UV problem was overcome and "fully-modern" LCD calculators, with today's familiar gray-colored display surfaces, became available. Because LCD models took much less power, replaceable batteries would last much longer. With the rise in popularity of pocket size LCD calculators in the later 1970's, LED and fluorescent display calculators all but died out.
Today, fluorescent displays are retained only for some desk-top models. Accompanying this decline, rechargeable batteries for pocket models equally faded away. Helping to push this trend was the rise of solar powered models.
#6 Solar Power
Solar power, another achievement of the Space Age, has also come to dominate today's calculators. Its adaptation to calculators first came in 1976-77, with pioneer models by Royal (Solar 1) Teal (Photon), and Sharp (EL-8026).
Yet, due to the relatively high initial cost and the relative inefficiency of the "first generation" of solar cells for calculators, it would take until the early to mid 1980's before the price and reliability of solar units compared favorably with the non-solar, cheaper models of the time.
Today in 1997, solar units (some with battery backups) dominate the calculator market, though fully battery-operated models also persist.
#7 Cheap Price
The earliest portable units of late 1969 to the early 1970's were expensive. Sharp's QT-8B in mid-1970 was priced at $495, while its EL-8 in late 1970 was $345. Canon's novel thermal tape display "Pocketronic" in February 1971 was introduced at $395. (And all this is 1970's dollars -- multiply by 3 to get a relation to today's prices.)
Indeed, the relatively high cost of ICs, plus a nice profit margin due to little initial competition in the emerging mass calculator market, kept even the smaller pocket-size calculators through 1972 over $100.
But with the high profits possible, dozens of companies jumped in. Calculators were marketed not only by many well-known firms like Royal, then a typewriter giant, and Singer, best known for sewing machines, but also by little upstart companies. And with increased competition and ever-cheaper ICs, the price of calculators continued to fall. With them, so did many manufacturers.
This period, dubbed, the time of the "Great Calculator Wars," took no prisoners! Even some of the early giants of the industry fell or left the business "licking their wounds."
As early as October of 1974, the JS&A company, which sold calculators through mail and magazine advertisement, offered the Texas Instrument TI-2550 for an incredible $9.95. For this period, a calculator under $10 was incredibly cheap! And that was not the end of it either. By December 15, 1976, the New York Times was advertising a Conic model for an even more astonishing $5.95. Truly cheap!
In the 1980's, $2 and $3 calculators were common. And so it has gone. Today's least expensive, often Chinese-made, calculators are found for $1 to $2, with many given away as "freebies" by companies for advertising purposes. You can't get much cheaper than free!
Today's Models - Still Amazing!
About 20 years ago, my first calculator, a "cheap" model from Radio Shack, the EC-221, was a four-function LED unit costing $10.95. That too, was an incredible machine considering the milestone achievements which had made it possible. Yet, as I have sketched in this article, the "evolution" of calculators leading to today's units was still underway, with today's models several "stages" more sophisticated than those of 1977.
Today, $10 at a Wal-Mart or K-Mart will buy you much more than a simple four-function calculator. And if the past is a key to the future, tomorrow's calculators will be even more sophisticated for relatively less money.
I was amazed in mid-1995 to buy a Radio Shack model EC-210 which recites my computations in nine different languages, plus has a time-alarm feature. All this for a mere $9.95 sale price.
Also, you can even find very inexpensive bright-colored, "talking" calculators sold for children! (The first ones were developed in the mid-1970s for the blind.)
I can only wonder what new major milestones will be achieved in the future evolution of these amazing little machines? Voice activation? More computer-like features at rock-bottom prices? Color displays?
In any case, it will be exciting to watch what really happens!
© Copyright Robert King 1997.
© Text & photographs copyright Nigel Tout 2000-2022 except where noted otherwise.