Friday Flashback #506

Earlier this week, David Pogue took a large Westport Library crowd on an entertaining, instructive journey through Apple’s first 50 years.

Scott Brodie remembers those early technology days too.  The 1970 Staples High School graduate writes:

Early in the “Harry Potter” series, as Harry ships off to Hogwarts for the first time, he stops by Ollivanders to purchase his first magic wand (rather, it chooses him).

It was much the same as a student at Staples in the 1960s. During the first week of Chemistry class, students took a few days out of memorizing oxidation states and valences to learn how to use a “slide rule” – a 17th-century contrivance which facilitated multiplication and division, even trigonometry.

Like Harry’s wand it came in a long, thin, dusty box, and was considered a major purchase on the way to competence in math and science.

A Pickett Model N3-ES slide rule just like mine, bought in 1967, with its leather case. The rule is set to perform multiplications by a factor of 1.25 (for example, 4.00 x 1.25 = 5.00). Scales on this side of the rule provide for calculations of products, quotients, reciprocals, squares and square roots, cubes and cube roots, sines, cosines, tangents, and inverse trig functions. Logarithms and exponentials were available on the other side.  No batteries needed.

A slide rule was a major purchase – equivalent to several weeks of one’s weekly allowance. Many of us went downtown to buy one at Klein’s or Fine Arts with our dads.

A good slide rule was expected to carry a serious STEM student through high school, college, maybe even graduate school. We tracked our progress in math and physics as we learned to understand the various slide rule scales.

I still have mine. With no batteries to go dead or worries about holding a charge, it still works as perfectly as the day it was new.

Computation had made little progress since the invention of logarithms and the slide rule (based on them) in the 1600s. They were the mainstay of most routine calculations in the design of the Mercury, Gemini and Apollo spacecraft that took Americans to the moon by 1969.

Accountants used simple 10-key adding machines. A few mechanical “calculators” — noisy boxes full of whirring gears — could multiply and, with luck, perform division.

But these were frightfully expensive, and available only in laboratories like Los Alamos, where the first atomic bombs were built. So we made do with slide rules, and tables of the values of the trigonometric functions.

State-of-the-art calculation in the early 1960s: (left) a Gilbert 10-key adding machine. With tedious effort, it could also multiply. Right: This Marchant desktop calculator could add, subtract, multiply and divide. The “carriage” at the top shifted left and right to provide for place value.

The first whiff of digital computers for students’ use arrived at Staples around 1968, in the form of a noisy Model 33 Teletype.

(Staples had a room full of IBM “tabulating” machines, next to the typing classroom – large devices, about the size of a sofa, which could sort punched cards, and perform simple arithmetic and printouts. They were used for scheduling, and printing student schedules and report cards.  Students were not allowed anywhere near them.)

The Model 33 Teletype banged out 10 characters per second, and communicated with a time-sharing mainframe computer at the University of Bridgeport.

It provided access to the BASIC programming language. Programs were stored on strips of punched paper tape, which could be re-read into the terminal for later use.

It was connected to the mainframe by an acoustic coupler modem. Users dialed the computer’s phone number, listened for the characteristic high-pitched sound of data coming down the phone lie, and placed the handset of the telephone on the connecting device.

Staples’ subscription provided for only a few hours of use each week – not nearly enough. Something else had to be found to address the growing interest in learning to use computers.

AT&T Model 33 Teletype computer terminal (left). The paper tape punch and reader is on the left side of the keyboard. Acoustic coupler modem (right). After dialing up a remote mainframe computer, the handset was placed on the device to pass signals back and forth, at a maximum rate of 10 characters per second.

The answer came in a new, state-of-the-art “programmable calculator”: the HP 9100A from Hewlett-Packard. A self-contained device, about the size of an IBM Selectric typewriter with about 65 keys, it allowed for data entry, storage and retrieval of a handful of 10-digit numeric values.

Unlike other electronic calculators of the day, it could compute trig functions and their inverses, and – uniquely – it provided logic functions, permitting creation of programs that could make decisions depending on previous results.

In 1968 it cost about $4,900 (perhaps the equivalent of $45,000 today). But it was “ours” – available to any and all in math classes, during free periods and after school, without time limits.

The next year the HP 9125a flat-bed plotter became available, allowing creation of high-quality graphics output.

Hewlett-Packard programmable calculator, model HP 9100A (right); associated HP 9125a flat-bed plotter (left).

We tried to outdo each other devising new and engaging applications, including solving surveying problems, calculations of trajectories and orbits, plotting theoretical curves of interest, and studying convergence of infinite series.

In 1972 Hewlett-Packard introduced the HP-35, the first pocket-sized “scientific” calculator. It was a miniaturized version of the HP-9100a, but without the programmable logic.

It sold for $395, still an astronomical sum for most all students (equivalent to about $3,000 today).

By 1974 knock-offs became available for $100. Slide rules became obsolete almost overnight.

By 1976, the cost of a “scientific” calculator was down to $25. The last high-quality slide rules were made in the late 1970s.

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