Saturday, October 6, 2018

HHC 2018 In Review

HHC 2018 In Review

HHC 2018 took place on September 28 and 29, 2018 in San Jose, CA.   If you have not gone to a HHC conference, and you love calculators and math, I strongly encourage you to attend.  The conferences take place typically around the latter half of September.

There will be videos from the conference in the upcoming weeks from  The following is a short summary of the talks presented in the conference.


I am under a non-disclosure agreement, which means that I will not be able to discuss certain details of the conference due to confidentiality.

Saturday:  September 29, 2018. 

Thomas Chrapkiewicz - Silicon Valley History

Chrapkiewicz takes us on a history of Silicon Valley.  Despite what most people believe, which included be, the term Silicon Valley did not originate int the 2000s.  The term goes back to Don Hoefler, who first used the term in his article "Silicon Valley in the USA" in 1971.

Some places of interest that Chrapkiewicz highlighted are:

*  A plaque dedicated to inventor Dr. Lee de Forest and the Electronics Research Laboratory, located on Channing Street and Emerson Avenue.

* The HP Garage, located at 367 Addison.

* Stanford University and Stanford Industrial Park.

* A plaque and semiconductor display dedicated to the Schokley Semiconductor Laboratory at 391 S. San Antonio Rd.  Even though Dr. Shockley of Bell Labs started the research into silicon devices, he had an infamous reputation, resulting of eight members of his team left Shockley for the competitor Fairchild Semiconductor in 1957.

Chrapkiewicz also highlights his career and how it lead him to Silicon Valley.  He now works in Audio & Acoustic Research at Ford Motor Company.  His current office is located where the Hewlett Packard sales and service was once located.

Namir Shammas - Polynomial Roots by Optimization

Shammas describes several methods to obtain the roots of the following polynomial equation:

p(x) = x^n + a_(n-1) * x^(n-1) + a_(n-2) * x^(n-2) +  ... + a_1 * x + a_0

where a_i are all real coefficients.

The properties known as the Vieta formulas are to be optimized to find the roots of p(x):

x_1 + x_2 + x_3 + ... + x_(n-1) + x_n = -a_(n-1) / a_n

x_1 * x_2 * x_3 * ... * x_n = (-1)^n * a_0 / a_n

x_1 * (x_2 + x_3 + x_4 + .... + x_n) + x_2 * (x_3 + x_4 + x_5 + ... + x_n) + ... + x_(n-1) * x_n = a_(n-2) / a_n

One method described is the Quasi Lin-Bairstow Method which reduces p(x) by the form:

p(x) - q(x) * b(x) + r(x)

q(x): a quadratic polynomial in which roots are obtained from p(x) at each reduction

r(x): a linear equation that servers a remainder

Another method described is a Durand-Kerner algorithm, which uses four equations for iteration to find real and complex roots for p(x).  The method is found to be effective in finding roots of polynomials with both real and complex coefficients.

Article from Shammas:

Sylvain Côté - HP-IL Compendium Presentation

Côté prepared an HP-IL Compendium, consisting of any information related to the Hewlett-Packard Interface Loop (better known as the HP-IL).  The Compendium took six months to complete.

The HP-IL is an interconnection bus that was in the use during the 1980's and 1990's, and serviced the HP-41C, HP-71B, HP-75, HP-80, and general computers.  The peripheral types covered by the Compendium includes controllers, storage devices, printers, plotters, display devices, modems, and other control and specialty devices.

Monte Dalrymple - 41C Flexible Module

Dalrymple introduces a 41C Flexible Hardware Module (FHM), which is a circuit board to be placed in a regular HP 41C.  The module is an upgrade which can facilitate the installation of the time module, extended memory modules, extended function module, service and printer service module, and MLDL (Machine Language Development Lab).

The module is a Lattice iCE40Ultra FPGA, which can be flashed once.  However, the FHM board contains a 32768 Hz oscillator and additional memory resources due to efficient use.

Also introduced is the GNSS module, a 4K ROM module, also made to fit in a HP 41C.  This module gives additional functions, essentially turning the 41C into a GPS system.  You can get the altitude, latitude, longitude, plus display format options and other ROM option commands.

Gene Wright - Old Calculator Ads & Unisonic Calculators

Wright presented a collection of old calculator ads from 1972 to 2010.  Wright also highlights the calculator lineup of Unisonic, particularly from the 1970s:

*  Unisonic 1040:  four-function calculator with a GPM button.  Noted for it's white, blue, and orange keys on a metal case.  It ran on either AAA batteries or a 9 volt battery.

*  Unisonic 767, 788P, 739SQ, 731:  These are also four-function calculators with additional functions such as reciprocal (1/x), square (x^2), and the pi (π) button.

*  Unisonic 931:  A small handheld four-function calculator.

* Unisonic CS-14:  This is a large four-function calculator with several metric-US conversions listed at the bottom.

* Unisonic CASINO 7 and 21 Jimmy The Greek:  These are both four function calculators with a blackjack game.

* Unisonic 796:  A scientific calculator with a shift key only for the inverse of the trig functions (asin, acos, atan).

* Unisonic 799:  A simple scientific calculator.  Your mileage may vary depending on which version of the 799 due to some of the productions had difficult to read key markings.

* Unisonic 1299:  The polar/rectangular and degrees/degress-minutes-second conversions are added.

* Unisonic 1499: Add hyperbolic functions (a [HYP] key), also had a red display.

* Unisonic 766:  A finance calculator featuring linear regression, cost/sell/margin calculations, and time value of money calculations.

It was seeing Unisonic calculators in K-Mart stores in Nashville is what inspired Wright to get into calculators.

Dave Cochran - HP Calculations from Desktop to Pocket

Cochran tells the story on how the HP 35 calculator came to be.  Cochran is loved in the HP calculator community.  He is fundamental in the development in both the HP 9100A and the HP 35, along with HP 65 card reader, the 204 oscillator, and the 3440 digital voltmeter.  For what the HP 35 brought to the engineers, scientists, and math enthusiasts in 1972, the first handheld calculator to have trigonometric functions, logarithmic functions, and power and root functions, it was no wonder why people lined up to pay $395 for this marvel. 

The HP 35 was awarded the IEEE Milestone in Electrical Engineering and Computing Award in 2009.


Felix Gross & David Hayden - Recreating the 15C Advanced Functions Handbook

Gross and Hayden went through the process on how the HP 15C Advanced Functions Handbook was recreated.  This mainly involved scanning images, recreating the examples, creating keyboard fonts, and lots of proofreading.  This results are outstanding and beautiful.

You can download the file here:

They also presented a recreated HP-10C manual.

Jim Johnson - What was the first Personal Computer?

Jim Johnson takes us through a time line and determines what was the first personal computer.  Some of the criteria Johnson defines include:

* The computer must be digital and programmable.

* The computer must be commercially available or be readily assembled via a kit.

* The computer must be ready to be use after the basic instruction manual.

The presentation takes us through, among others, the IBM PC (1981), Apple ][ (1977), MITS Altair 8800 (1975), even the HP-65 calculator (1973), Xerox Alto (1973), HP 9830A (1972), Kenbak-1 (1971), Minivac 601, even the GENIAC (1955) before arriving at the Simon (1949).

Why the Simon?  The Simon was a computer kit first described in the 1949 book "Giant Brains, or Machine That Think".  The book provided plans to build the Simon computer, and influenced further development of interactive computers.

Johnson ended his presentation with demonstrating his Altair 8800.

Richard Nelson - Add SIG to FIX, SCI, & ENG?

Richard Nelson is a fan of significant digits, especially when it comes to working with analog meters and digital meters.  Nelson states that significant digits are needed and are useful for digital specifications, consistent accuracy, scientific calculations, and reporting results in technical publications.

What are significant digits?

*  Any non-zero digits (1-9)

*  Any zeros between non-zero digits

*  Final zeroes that is followed by a decimal point (aka trailing zeroes).  This can be tricky.  The number 1000 has 1 significant digit, but the number 1000., with the decimal point put after the final zero, has 4 significant digits.

In the proposed significant digit mode, you are required to enter numbers with that many significant digits.

Rounding presents a challenge, particularly the extra digit is 5.  Example:  rounding 13.5 to the nearest integer.  One proposed method is the Banker's method.  The rules for Banker's method are the same except when the extra digit is 5.  In the case with .5, the number gets rounded to the nearest even integer.


12.5 gets rounded to 12, while 13.5 gets rounded to 14.

To my knowledge, no calculator currently has a significant digits rounding mode.

Sunday:  September 30, 2018

Thomas Chrapkiewicz - HP-48 RS-232 Plotter Demo 

Chrapkiewicz demonstrates printing programs and text from an HP 48 to a HP 7550 plotter.  The plotter,  introduced in the mid 1980's, handled four sizes of paper:  type A (letter size, 8 1/2 x 11 inches), type B (legal size, 11 x 17 inches), A3 and A4.

All commands dealing with the printer were required to be terminated by a semicolon, with labels ending in 03h.  The text is ASCII.  Furthermore, the plotting space is limited by hard-clip limits and soft-clip limits, the latter determined by the user.

Richard Schwartz - Naive Testing of the 997x Random Number Generator

Using a WP-34S, Schwartz tests the reliability of random number generators.  One of the most used involves the multiplication of 997.   As far as the random number generators involving successive multiplications of 997, your mileage may vary on which random seed you start out with.  Seeds like 1, 3, 7, 17, 21, 23, 41, 43, and 0.200001 are good but any multiple of 2 or 5 isn't.

Schwartz looks for the random number generator to have a uniform distributions and uses the power spectrum, moments, and the Chi Square (χ^2) test are criteria.   With the χ^2 test, the comb factor and the number of bins are used to further investigate the distribution of the random number generator.

Thomas Chrapkiewicz - HP-48 Audio/Acoustic Performance

Chrapkiewicz tests the audio performance of the HP 48, HP 48GII, and HP 49g+.  He states that the original beeper on the HP 48 is louder than later calculators, however, the tones were more sinusoidal on later models.

*  Signals can be characterized by a linear combination of harmonics, such as a Fourier Series.

* The microprocessor's clock rate determines the audio frequency of the calculator.

* The hearing capacity of a bat exceeds the hearing capacity of a dog, which in turn exceeds the hearing capacity of a human.

* The calculator's beeper can be use to set up tones that beep on the hour, minute, even set up alarms.

*  The Bifurcation diagram, set up by the equation x_(n+1) = (x_n)^2 + c where x_0 = 0, is a visualization of how tones bifurcate with each successive calculation.  With this, as c decreases, particularly towards 440 Hz, the successive tones get more chaotic.

Side note:  I wish the HP Prime had a beeper, it was one of the things that made HP calculators unique.

Namir Shammas - New Algorithm for Numerical Integration

Shammas explores an alternate algorithms for numerical integration, the HFVQI (Half-Function Value Quadratic Integration).  This involves calculating the midpoint between the integral limits and performing an inverse Lagrangian interpolation using the following points (a, f(a)), (b, f(b)), and (c, f(c)), where c = (a + b) / 2.  An advantage of this method is that you can reduce the number of intervals needed to reach good accuracy.

For detailed formulas, click here for the Shammas' article:

Benoit Maag - Re-purposing old TI Calculators

Benoit Maag talks about how he re purposed two classic Texas Instruments calculators, the TI-1200 and TI-1250.  Despite the limited amount of keys, Maag has re-purposed a TI-1200 into the RPN -1200 and a TI-1250 into the RPN -1250.  This is done by replacing the microchip with a reprogrammed microchip with a driver.

The RPN-1200 has a Microchip PIC 18F2550 with a MAX7219 LED Driver and a 5V power supply, while the RPN-1250 has either a PIC 18F2550 or 18F2680 microchip with a MAX7219 LED driver.

What are the results?  A full functional RPN scientific calculator.  The RPN-1250 is a programmable scientific calculator, similar to an HP 29C.  The RPN-1250 has 98 steps with storage and recall arithmetic, indirect addressing, a host of US-metric conversions, and three slots to save programs.

Maag also had to reconfigure the display, which proved to be a challenge.  Each character has 7 LED segments.  Some letters ended up a capital letters while others were lower case.  Below is a sample.

I won his RPN-1250 as a door prize, it's truly one of a kind, and I plan to post more details about it in a future blog post.

Door Prizes Won from the Conference

HP 11C:  I won it because I won a programming contest!

RPN 1250:  One of a kind, re-purposed calculator made by Benoit Maag.

A HP 71B case

Omnibook OB-425 with 4 MB Memory with OB-425 ROM System Card - a 1990's laptop

More to come!


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