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| The HP-35 scientific calculator Image via Wikipedia |
The HP-35 measured 79 x 147 x 34 mm, pretty chunky by
today’s standards, but ultra-sleek in its day, when a computer still filled a
small room. It ran on rechargeable batteries, and its electronics used several
integrated circuits. ‘Scientific’ meant the calculator was able to perform
logarithmic and trigonometric functions with one keystroke. It featured a red
LED display which could give scientific notation up to 10 digits, with 2 digits
for an exponent (power of 10).
The price was reduced several times, eventually to $195 in
the US. But this was, of course, still too high for the HP-35 to become a
mainstream part of classroom teaching. Production of the HP-35 was stopped in Feb
1975, 3 years after its launch. 300,000 units had been sold.
The numbers and functions for calculations were entered in
"Reverse Polish Notation". This would seem very strange to today’s maths
students, since the operator always appears last: a calculation such as 3+5 was
performed by typing “3 5 +”. It avoided the need for parentheses or an "="
key.
Further models from HP followed. The introduction of the
HP-35, its descendants and similar scientific calculators by Texas Instruments
soon brought about the demise of the slide rule in the classroom.
The appearance of the calculator gave rise to the “should we,
shouldn’t we?” debate in the media and among educators, with some feeling
strongly that the introduction of a calculating device would bring about a
decline in students’ own calculating abilities. These arguments had little real
relevance in the early days, since the cost, fragility, and short battery life of
these early machines meant the calculator had limited use in the classroom, and
was certainly not available to every pupil.
By the early 1980s, those deterrents began to decline. Solar-powered
scientific calculators began to appear, with hard cases, costing around £20. The
UK exam boards bowed to the inevitable and made them a standard piece of
equipment in O-Level and A-Level mathematics. The calculator was here to stay.
Later, the first hand-held calculators appeared that could
graph functions. Like their simpler counterparts, these calculators were too
expensive to be widely adopted when they first appeared, but today many schools
encourage their use, although they are still not all tolerated within
examinations.
Nowadays, the line between a calculator and a handheld
computer is very blurred. Some calculators such as the TI-89, the Voyage 200
and HP-49G are able to differentiate and integrate functions, solve
differential equations and run word processing software. Other handheld devices can, of course, connect
to the Internet. Whether such devices will ever be used in our exams, only time
will tell.
An emulation of the HP-35 is available for the Apple iPad.
