A few words ‘n thoughts on the weirdest calculator I’ve ever held in my hand, the notorious HP 38G

Hewlett-Packard manufactured this crazy pocket calculator (not really one for the pocket, to be honest) between 1995 and 2000 at a relatively low price of about 80 US dollars. It broke with tradition in so far as it had no RPN logic. But that’s not what makes this device peculiar, I consider its overall design simply grossly flawed, and these are my three proofs:

1. The keyboard allows direct access only to quite a few mathematical functions. These are trigonometric operations, exponential functions (root calculation included as well as e-based operations), logarithm (decimal and natural), and matrix definition. And the four basic operations you simply cannot omit without getting admitted to an asylum. This is really not much functionality directly at your fingertips! All the rest of the built-in mathematical procedures must be retrieved using the MATH key which opens up a split-panel window with a main category on the left and functions on the right. Since the machine operates at a remarkably low speed it often takes noticeable amounts of time to build up the list, and even if your function isn’t buried too deep in the catalog this process of finding and choosing a function really does feel awkward and time-consuming. Thus, the machine is not designed to calculate fast and efficiently more than only basic terms or formulae.

2. Even simple arithmetic tasks take a noticeable amount of time until a result is being displayed. The calculation 15689/23.3 takes so much time that it feels like a whole second until the result appears. The function plots however are calculated relatively fast for a machine of this era, manipulating plots and working on this screen takes place at a decent speed.

3. Programming (and entering text in general) is kind of a nightmare. It is hard to find some way of illuminating the calculator so that one can read the letters adjacent to the keys fast and reliably enough. Typing in text and editing it is extremely slow (in most cases I use the A…Z key PLUS the key for the character needed, and if you need lower case letters you have to press SHIFT, A…Z and the pertinent key for the lowercase character you want), and in addition, many often used characters can only be retrieved using the CHARS key which opens up a matrix of characters you have to navigate with the arrow keys. It is possible to get several characters entered into your text without leaving this screen which helps a littlebit but that’s only a drop in the ocean. Don’t say: Use the programming functions catalog! It is faster to type DISP by hand than grabbing it out of the catalog.


The basic concept of ApLets found its way even to the latest HP calculator, the HP Prime. In so far, the 38G was ahead of its time. What’s missing is speed. And a lot of speed. The LCD reacts in snail mode, and this demolishes the whole user experience although the basic calculation speed seems not to be as bad as the user interface feels! A real problem is also the lack of useability for the one being busy calculating complex terms, especially if he needs more advanced mathematical functions which are all buried in a catalog and can’t be reached via a direct or shifted keystroke. Programming is extremely hampered by the bad interface but offers rather nice commands to set up a convenient user interface. But the fun of programming is minimized by the effort necessary to type in the whole program. On the bottomline you have a feature-rich calculator with an interesting internal structure which is neither ideal for the mathematician or engineer at work nor for the enthusiastic programmer. Even the least demanding user will notice the low performance of the user interface and grab a more simple machine which instead responds immediately.

Closing words

If you don’t need a workhorse and are not in a hurry, you may discover a feeling of sitting in a Cadillac using this brick. With its patented cover and the enormous gumfoot on it, together with a huge chassis this thing reminds you to just take your time and slow down into the comfort zone. And if you have, like me, the time to explore its internal structure and secrets, you may even start to love it.

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