Stefan's Historical Computing Devices

Review: HP 35s Programmable Scientific Calculator

Sat, 19 Jan 2008 22:27:45 GMT

Most modern HP scientific calculators fall into two classes: graphing and ugly. The last decent calculator made by HP was the 32sii, an RPN programmable with equation solving and integration. The follow on to this was the 33s, which took a previously nice design and made it into one of the ugliest HP calculators I've ever seen.

With the HP 35s, Hewlett-Packard has attempted to return to its roots, at least in appearance and quality. HP produced the 35s as a successor to the 33s, and at the same time as a celebration of the 35th anniversary of the very first scientific pocket calculator ever made, the HP-35.

HP-19C Programmable Calculator

Fri, 23 Nov 2007 02:51:30 GMT

When my HP-42s broke down in 1998, one of my colleagues (also my former grad supervisor) gave me his broken HP-41CX and HP-19C. I described how I repaired the 41CX in another article. Here we'll take a look at the 19C.

The HP-19C was one of a matched pair of high-end programmables in HP's "20 Series" of calculators. The 19C was the printing version of the 29C, which in turn was an improvement over the similar looking 25C. With the exception of the printing functions, the 19C and 29C shared the same keys, although in a different arrangement.

Matrix Multi-Tool Update

Mon, 19 Nov 2007 01:45:06 GMT

I've made a minor update to the Matrix Multi-Tool to make the matrix dimensioning code and the matrix solver code into subroutines that can be called from other programs I plan to write in the future.

A Matrix Multi-Tool for the HP 35s Programmable Calculator

Wed, 07 Nov 2007 02:15:14 GMT

This is my second attempt at a large program for the new HP 35s programmable scientific calculator from Hewlett-Packard. My previous program addressed the curve fitting shortcomings of the 35s (compared to the HP-41C/CV/CX with Advantage Pac, or the HP-42s). This program is a start at doing the same for matrix functionality.

The HP-15C was the first calculator to introduce comprehensive support for matrix operation. HP quickly added equivalent functionality to the 41C series with the Advantage Pac, and the 42s came with these operations built in as well. The HP 35s does not have any general purpose matrix operations built in, although it can solve 2x2 and 3x3 linear systems.

The program I present here is a long way from being as powerful as the facilities provided by the 15C, 41C/Advantage, or 42s, but it does provide several useful matrix operations in one simple tool. It is loosely modelled after the Advantage Pac matrix program, which provides an easy-to-use subset of the functionality of the matrix library.

Aristo Multilog Nr. 970

Mon, 22 Oct 2007 01:26:09 GMT

When I first began collecting slide rules, I made a list of the ones that interested me the most, and then started monitoring eBay and the local antique stores. The Aristo 970 was the first to come up that stayed within my price range, and was thus the first slide rule that I purchased.

Curve Fitting for the HP 35s Programmable Calculator

Thu, 18 Oct 2007 01:31:27 GMT

Both the HP-41C/CV/CX Advantage Pac and the HP-42S calculator contain a curve fitting function which can fit a sequence of (x,y) data pairs to a straight line, logarithmic, exponential, or power curve. The much newer HP 35s will only fit points to a straight line. The manual provides a program to handle the other curve types, but that program has two drawbacks: you must decide in advance which curve you want to fit to the data, and it uses up a large number of labels (the machine has only 26). The program presented below rectifies both of these issues. It uses only a single label, and it allows you to fit multiple curves to the same data set. Like the HP-41/42 programs, it also has a best-fit mode wherein it automatically chooses the curve with the best correlation coefficient.

Stefan's Historical Computing Devices

Mon, 15 Oct 2007 00:20:44 GMT

Stefan's Historical Computing Devices web site is for the slide rule and calculator (primarily HP) enthusiast. I have a weakness for old technology. It's not that I don't understand the new technology (I'm a software architect for a leading developer of high-end mathematical software) but there's something I find charming and elegant about the devices used in simpler times.

On this new site, I plan to showcase my slide rule and calculator collection and post articles of use or interest to fellow collectors and users of slide rules and calculators.

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