Musings and comments about our common interest
As the HP41 repair book has already passed the 500 units sold mark, I have been challenged to write a book on the HP15c.
Many years ago, there was a book called "An Easy Course in Programming the Hp-11C and Hp-15C (Easy Course Series)", by Ted Wadman and Chris Coffin, which I have not been able to get hold of. Then you have the fantastic user manual and also the Advanced functions manual - in itself a computer science crash course. Then there are many sites that have several programs, but nothing like a common respository with all known applications.
I am not the only one to love the HP15c. Its compact form factor, the ability to use it with both hands for a faster keying in, the complete and consistent fucntion set, the good memory sze for its time, made it a formidable calculator for the engineer and scientist calculation, when he was far from a computer. I still use it every day and the search statistrics of my site still show it as the most searched item - after all these years.
The manual will describe the machine, list its several versions, explain how its firmware can be upgraded, and will list many programs for all areas of scientific knowledge and for all educational levels. Most of the information is already available if you know how to search for it, but I have missed a place where you can read all of it with a consistent writing and enough explanations on what each program is doing.
You may say that it does not make sense to write a book about a discontinued calculator, but I know for a fact that there are many of them still in use around the world, with peaople searching for software and longing to read more about it.
Besides, I do not lose the hope of having it produced again...
I am having a discussion with my son, an engineering freshman. He's just finished the first year, and he's very happy and thankful of having the HP Prime calculator. Probably it is the best calculator for a student nowadays. I have the feeling that the HP50g is the better calculator, due to its more "elegant" programming model; however, the Prime has more raw power and is easier to program is a procedural language similar to basic. (It is surprising what can be done with this language. You can take a look at the games that have been programmed with it in hpcalc.org. I hope that my children never see it or there goeas another distraction more)
My discussion with him versed on the fact that the HP15c is the best calculator to master "for the rest of his life". I see no point in having him using a HP41, even the cel: is a cumbersome machine that will occupy a lot of room in wherever he puts his things; The hp42s would be an alternative, but even that one is a little too big; but the HP15c is exactly the right size and has everything the prospective engineer needs - short of anything a computer spreadsheet or Mathematica or Mathlab can do. Plus, it is small enough to be really portable and carry it on your jacket pocket; and it keeps the utter elegance of the HP50g we were discussing about.
I plan to have him learn how it really works. He'll have one as heritage, and he'll be thanking me for it in the long run. I guess that the Prime will not see much use after he has finished college!
I will give it to him with the leather case to increase the acceptance rate - by the way!
This week I have been using the HP15c in my normal work. for that I have entered several financial programs including the Time Value of Money program. It is a long program but it makes use of many of the programming techniques in the HP15c.
The HP15c always surprises me regarding how cleverly distributed the keyboard is, and how well thought out is the function set. Most of the functions can be applied to complex arguments; also, compared with other HP calculators (including the advantage pack for the HP41c), the complex mode doubles the RPN stack and so programs can be applied to real or complex numbers, depending on which mode the calculator is; it allows to redefine the upper 5 keys; and you can combine complex numbers with the integrate and solver features.
A surprising capability on a calculator this size is the extended use of matrixes - you can invert matrixes and can also use them to solve linear systems - which is something you can do in an exam whithout anyone noticing that you're using your calculator. Also I liked how elegant is to solve an equation system: after entering the 3 matrix dimensions (coefficients, independent terms and results), you enter the values for each term in the matrix, and then you recall the independent term vector, you recall the coefficient matrix, and then you just press the divide key! then you have the result in the results matrix. So powerful, and yet so simple and elegant.
The calculator came initially with two manuals: one was the user manual, roughly equivalent to that of the other calculators (but with many more functions, of course); however, this was a machine devoted to scientists and engineers, and it should explain them with details how it works and what are the limits of operation and accuracy in the different functions and features. So, the machine came with an "Advanced Functions Handbook", pictured besides.
The manual dealt with the following topics (reading from the index):
These subjects are dealt with detail and combining precision and clarity - a must read for any computer science student!
The previous anniversary version did not have this manual, only the User Manual. Let's hope that, if this calculator is ever resurrected, it comes with this manual too!
I have created a "HP15c Corner" in our website. Something tells me that it will be useful some time soon. For the time being, we will put there all the HP15c or HP15c LE that we get for sale, and all parts and accessories related to them, including leather cases, battery covers, etc.
We'll also take care of the links to this wonderful calculator that we may find, as well as all the software for it that was available at the time.
We have sold the last unit of HP41CL. So far there are no more made and no more planned - and it will be difficult to produce more since there are many parts that are out-of -life. The board would require a deep redesign which current demand does not warrant - so it is a pity for all of us!!
One of the last units sold was a 1937A serial number unit - one of the very first. I have only seen an earlier unit, a 1932A. It is a nice closing to the story, 43 years after its inception in 1979. I was there then and I remember the lust for that powerful machine, far from me as primary student. My father bought instead a HP33c for me - which hooked me into RPN - a hook that I have not been able to unleash so far.
With the so-far demise of the HP35s, there are now the HP12C, the HP12C platinum (which has an RPN mode), the HP17bII+ and the Prime as RPN machines. So far in Europe the HP12C has been absent for some time, but I have been promised that it is returned - so far that I have been able to place an order for them. I expect the order to arrive before month end.
We are missing a RPN scientific (not graphical), preferably of small size, not competing with bigger student units. I have been given hope by the current calculator management - let's see!
Now that the calculator business is in the hands of Royanl and Moravia, let's see what could be our wishist, now that the HP35s has been discontinued. A customer called me on Friday, and he told me "I want a RPN scientific calculator" - then I realized that there is no scientific RPN calculator anymore!!!
Rumours are that the HP12c will be put again in production (despite being in some dealers' inventories, it has been discontinued for at least 4-5 years). This would open the door for other Voyagers calculators - and I am thinking about my long time love - the HP15c - again.
Among the units in production we have the HP17bII+ - which is an excellent product and the most powerful current financial calculator. However, it has the same body and key disposition of the HP42s - so that is another possibility for a scientific calculator (the HP42s has not been bettered in my opinion) - with limited development time (both models could eventually be run on emulation layers with the original firmware)
However, the calculator market is based on school needs. These are best covered with the 300s+ and 10s+, and then with the Prime as graphical calculator (which runs circles around most of the competition).
I will try to send these thoughts to Moravia, who has been for some years my distributor.
This week we have sold an original HP15c in bos, and in pristine shape. While I was reviewing its compact box, the instructive manual and the machine itself, I kept thinking that it was the best hp product ever.
Capable of inverting an 8x8 matrix, solving equation systems with complex numbers, and having all keys with three different functions (and in some cases 4), it has the most elegant logic of all units I have seen. Nothing is superfluous, nothing repeated, everything has a purpose. And it is compact and beautiful - the ideal lab calculator.
Here are some pictures of it:
We have located a boxed, pristine example of one of the best calculators ever made: the original HP15C.
We have the manuals, the box and the case. The calculator itself is essentially perfect:
The price is going to be high - around 400€, since we had to pay dearly to get it. This is one of the cases where I am not really sure of selling it - I also want it for myself!
We are not posting it in the web until I have the time to properly test it - but if you are interested please send an email to firstname.lastname@example.org
Old HP machines!
We’re now in the wake of the new major release of Mac operating system, Yosemite. There will be a number of new features but also correction for many small errors of the previous software. This is typical of today’s software: due to its own complexity, it is bug-ridden, and unsafe in many respects.
Compare that with the 12k * 10 bit of the assembly code of the HP15c. That code was crammed with fantastic mathematical routines that allowed that calculator to perform matrix operations, integrals and solve formulae. Most of the HP15c that have not been physically battered are still working. And talk about battery life. Around 8 pm I receive a 10% battery left message from my phone, while the original HP15c could last up to 15 years with the same battery pack. It could not be upgraded, but there was no need to: it was the ultimate pocket calculator, with everything a science practitioner would ever need, short of a true computer.
Wherever I look into the logic of the HP15c, it seems to me one of the best objects ever designed by mankind. It is the ultimate “less is more” machine. Apart from all keys having three written functions on it, some of them have more: the same key has completely different meanings depending on what you’re doing.
It had 10 digit precision, which was state of the art at the moment for a pocket calculator. Nowadays 14 and 16 digit are normal - however, when in reality you may need short accuracy? And it is not so important the number of digits, but the number of accurate digits. And the HP calculators of that era had absolutely first class algorithms. Most were create by Mr. William Kahan. They were created in machine code, so that it could run as fast as possible with the hp15c hardware.
It used a version of the nut processor (the same as the HP41c), running at an speed that appears ridiculous today: 244 kHz (yes, not MHz), and it took several minutes to perform a 8x8 matrix inversion.
The algorithms were so good that, when HP started the project to reissue the HP15c based on new, modern hardware, they decided to use exactly the same firmware, running on an emulation layer on an Atmel ARM-type processor. There have been several problems in adapting the old firmware to the new hardware - the pause function does not work well, and the low battery indicator does not function in time - at least for me.
But apart from that, it is as good as the original - just 100 times faster!
It is a pity that there are no more stocks of either one!
Leaving for holiday in a beach location. Still some work to do, but having been warned by “home management” that there are lots of things to pack from our children, and therefore I need to “travel light”.
Hearing “travel light” from my wife is at least surprising: she does not know what “travel light” means. My bags will will always be half of her’s - but let’s do the exercise anyway.
Which for the sake of this blog means which calculator(s) to carry with me. I have already decided not to take with me the HP41CL, although is the one I like best. It would be my solitary island choice - but not for a summer travel to a sun and beach destination. Too risky for its high value. So I have left it in Oslo.
I am taking with me the HP Prime. Now the question is whether I should take with me an HP15c - the HP42s suffers the same precautions as the HP41CL.
The main thing against the HP15c is that I will lose 1 hour with it at the beginning. Why? Because it lost all of the programs I wrote in it (235 steps of ugly code to fill in, with a lot of chances of getting some of it wrong). And I am used to my programs when working. I have it anyway on my Iphone.
And why the HP Prime and not the HP50g (with the promised comparison between both)? First, if we have to travel light, the Prime is thin and light. With its plastic cover, is probably the best protected calculator I ever had. What’s more, I can try to use it to get some of my children interested in maths (through calculators)
Then, why not both? That’s a question that I still need to answer to myself. After all, we’re only leaving next wednesday morning!