Contributed Columns

Like the hilarious "HP-25 PRINTOUTS?" article, the following article is a parody of the crazy stuff that appeared so often in 65 Notes and the PPC Journal. More than anything else, it tells me that HP calculator enthusiasts still have the same insatiable curiosity that they did back then.

Enjoy this glimpse into The Way Things Were... 19 years ago!

-Joe Horn-

THE PITKIN TAP
John D. Hirsch (2552)

"PPC Journal," January-March 1979
Volume 6, Number 1, Page 26

Having a friend who is a professional window washer in Corvallis, and a very nosey type, has given me some advance information on the next generation, top-of-the-line HP-86.

So far my window-washing pal has only been able to come up with information on two features which are finalized -- but they are very intriguing.

The HP-86 will have a small pushbutton switch on the top of its case, about 1 cm. from the right edge. The function of this switch will not be documented in the Owner's Manual and the switch will seemingly do nothing. When asked about it, H-P engineers will intimate that it was part of an unimplemented feature cut by budget considerations.

Not long after the HP-86 comes out, a PPC member will write an article showing that a simple jumper connection from this switch can be implemented to change the direction of the card reader motor. When the switch is activated, cards read backwards, and the program is loaded last instruction first. The article will not explain why this is an advantage, but PPC members will all modify their calculators anyway in an attempt to further explore this interesting behavior.

The second HP-86 unsupported feature will be revealed in PPC shortly thereafter. When the "f" prefix button is held down while "LST X" is keyed in 3 times, the "1", "2" and "8" digits are pressed simultaneously, and the HP-86 is rapped sharply on the right side of the case, a running program will crash, and the calculator will begin flashing random digit segments in the display, causing pretty patterns.

This feature will be accidentally discovered by a naive engineer from Minnesota named Harvey Pitkin. He will write a letter to PPC asking if there is something wrong with his calculator, and should he send it in to be repaired? Although he will not realize it for some time, Pitkin will be immortalized as the discoverer of the so-called "Pitkin Tap."

There will be a rash of articles in PPC on the Pitkin Tap. The digit segments flashed in the display as a result of the Pitkin method will be recorded and published in tabular form. An attempt will be made to correlate the pattern of display flashes with the force of the tap. Another article will suggest that the pattern of flashes can be related to the calculator's internal code and further elaborate tables will be published.

Pretty soon a few indignant PPC members will be writing in to say that the Pitkin Tap does not seem to work on their HP-86's, and should they send them in for repairs?

To answer these complaints yet another article will be published showing that the Pitkin effect can be reliably produced by adding only a few diodes and transistors to the HP-86, and then running a jumper to the convenient pushbutton switch at the top of the calculator.

Once the Pitkin Tap effect can be reliably reproduced on demand, a PPC program will be published to flash messages in secret code, which can be decoded only by another HP-86 with Pitkin modifications. The program author will claim that it works even better than the Star Wars secret code ring he ordered from an advertisement on the back of his Shredded Wheat box.

PPC will then begin publishing articles in this secret code. When new members write to ask what it all means, they will be advised to buy the last 44 back issues and study them carefully.

Meanwhile a young H-P project engineer will meet Richard Nelson at a trade show and will happen to mention that the design of the HP-86 was heavily influenced by reading PPC and tabulating all the articles by area of interest. The conclusion was that PPC members were most interested in seeing more unsupported features on the next generation of calculators, especially if those features were difficult to reproduce and required hardware modification.

My window-washing buddy is scheduled to do the windows in the calculator R&D section again in just a few weeks. I'll let you know if he has anything more to report.

John D. Hirsch (2552)