Calculator blog

I was trying to do some hours calculations, in order to add up how many hours have been spent on a project in our business. I was using the HP Prime, and did not feel like looking in the manual for too long. From memory, I did not remember to have seen the HMS-type functions in the manual. How could I do it, then?

There is the º’” key in the first white keys row. When entering the firs number (5h30 min), i just pressed 5 > key > 30 > ENTER, and I have the right number in hoursºmin' on the stack. Then I enter the second number (4h25), like 4 > key > 25, and it shows just right again on the screen. If I just add, then I get the right answer, 9h55. Then, this means that the key works like a help for writing the number. But if I now press again the key, while having the result in the 1st level of the stack, it gets automatically converted to a decimal value. Pressing it again reverts to the hours format. It seems that in this case it is only switching between representations, not really doing any conversion. It is definitely a very clever way of handling deg/min/sec, or for that matter h/min/sec quantities.

Now I need to prepare a couple of programs to handle the date calculations...

Now that the HP Prime is close to arrival, I would like to share several comments about it.

First: it is a future-proof architecture. Remember the bug lists of the HP35s, still unresolved? The Prime can be easily retrofitted with the latest firmware - very much like the HP50g, but with a much simpler process (at least from what I remember the last time I did it, for firmware 2.15). In fact, during the test period, there have been several firmware versions that improved upon the previous ones.

Second: the connectivity software is very much ahead of the previous HP connectivity software. You can see variables and programs, with much better screen formatting in your computer, and the possibility of directly writing on the Prime’s memory.

Third: battery duration. Remember that the machine has a color screen, that it is much more energy-demanding than the past LEDs of the HP50g and before; In addition, it comes with a telephone battery. All this would make you think that it would last for 1 day only before recharge - the same as your current smartphone! Well, I have been using the machine for office use during the last 3 month, and when I have reconnected it to a power supply (not every day, by the way), it was never below 75%. This machine is much more energy efficient than a mobile phone.

Third: you have 2 separate worlds: CAS and Home. You can have RPN in the home environment, but not in the CAS one. Beware: the behavior of your programs change depending on your choice of RPN or algebraic, and on your choice of decimal comma vs. decimal point. You need to make your programs based on that choice. What is syntactically error-free in one case, may give errors in the other.

Fourth: You can reassign the whole keyboard. So if you’re in finance, you can assign the %, %CHANGE and %TOTAL to the SIN, COS and TAN keys, and activate the user keyboard - just like your dear HP41c does. However, it is just like their RPL brethens: it consumes both arguments to the function - not the way you're used with RPL. To do that, you need to do some programming

Fifth: Keyboard feel. A very clear action, but on a very short displacement. I have never experienced a failure: either a click that does not register, or registers double. Here is better than most of the recent calculators. But forget about the feel of your HP41c: you will not have it (for me, the keyboard I long to return to all the time, in particular the tall version of my HP41CL sample)

Sixth: Screen. The fact that you can touch the scree to select whatever you want is amazing. As you may know, I work in finance, and one of the things I need to do from time to time is exchange rate calculations. For that, I have created several variables, that I can select just by pressing VAR and clicking on the touch-sensitive screen. Miles better than the variable selection in any RPL calculator! Once you do it this way, there is no going back!

Here you have an example. I have created just two variables, storing the €/norwegian kroner and the €/USD. I can now select any of them with my fingers, ready for calculations:

There are several HP-related news to give to you.

First, there is a new issue of the HP Calculator Newsletter, corresponding to September. It is mostly devoted to the HP Prime. There is a thorough description of this new calculator, and another article from HP calculator amateur Namir Shammas. His articles are always very interesting; and in his personal website you can see a wealth of programs for different HP platforms.

Here is a link for the calculator newsletter:

http://h20331.www2.hp.com/hpsub/downloads/hp_calculator_enl_sep_2013_v2.pdf

On a different tone: there is a television broadcast in the US about the Prime. You will need wait for a minute until the Prime appears:

http://www.designingspaces.tv/show_segment.php?id=1330

Interesting moments are approaching. HP has decided to go for the educational market and they are employing all their creativity and marketing clout. It will be a very interesting battle!

Please find another youtube video about HP Prime:

• We can already share the Emulator that will come with it. You can have a real taste of how Prime can work for you. You will find it in the emulators' page and in the product page as well (as soon as I am finished with everything!)
• I will post the manual as well, as it is contained in the emulator software. It will give you a taste of the Prime, and together with the Emulator, will help you with the buying decision
• So far, I will not post the connectivity kit, since it is no use for it unless you have a Prime yourself!

When pressing the floppy disk icon, your program is in your calculator! (incidentally, the program assigns a function to a key in the user keyboard. All keys can be assigned a new meaning!

Stay tuned for more Prime news!

As most of you know, HP will market the new HP Prime in late september 2013. I have been playing with one of the prototypes. The color on its back is textured white. We have been told that the final model will be textured black. It will make it more “professional” in aspect - on the back, since the front is perfect already. There is a plastic cover that is a departure from old leather-like calculator cases of yore. However, it protects well the calculator screen against direct hits and accidental drops.

This machine is thin! Much thinner than the 50g it supersedes. part of the reason is that it uses a cellular phone battery - itself much thinner than even AAA-type batteries. It is impressive in a professional desk, and it was the chat of all engineers in the office.

The unit has been designed to be upgradeable through firmware versions. It was a breeze to upgrade the firmware to the latest version, and I used the virtual Windows XP session in a Mac, so no need even for Vista to be able to upgrade. The newer version has better fonts and probably less bugs - not that I am able to find any significant bug with my scarce experience with it.

One of my main concerns about a calculator is the keyboard feel. HP units of yore always excelled in that. Lately, HP units have been a little bit of hit and miss: the HP35, HP15c and silver HP17bII+ are excellent, while the HP50g, 39gs, 40gs are barely enough. Prime is a little bit like the HP30b: small distance to get the click, but once gotten, the key press is clear and there are no missed or doubled keys. In this respect, it is even better than the HP17bII+.

It is as well a discovery to be able to navigate around the menus with your finger - it gets you there much faster. Also, in some graphical apps, is nice to change scale by pinching in or out with your fingers, or moving upwards or sieways to the graph areas of interest. Remember the HP50g scale screen, and how many times you needed to go there to get a good view of what you were doing? No more!

Enough for today. Tomorrow, more! 

If your HP41CL seems to lose the configuration after a low battery sign, or a change of batteries, and you are fearing to go through the whole installation procedure, do not fear! You don't need to do that. If you have assigned some keys using functions from a plugged in port, and you see XROM xx, do not worry: the memory loss has not been so big or so long as to lose the keys assignments, and therefore most likely the whole setting can be reinstated.

You just need to reenable the memory management: XEQ MMUEN. This will make the calculator again aware of the whole memory area. You can now use re-assigned keys and see that they keep the right function name on it.

This method does not work when you receive the dreaded "MEMORY LOST" message (below that of the HP41CL when it was born!)

Sad news...

I have received a mail from the designer of the circuit board of the HP-41CL (Monte  Dalrymple), where he tells me that he has run out of units in his last production batch. He will only restart production in case there is enough interest on it. So, if you were planning to buy one, you're out of luck for the time being.

However, you can try to make a free reservation, just by sending an email to jose@thecalcuatorstore.com, so that I can forward to monte together with other requests ( I have already three of them)

• 5 graphing apps (blue) to explore graphs –including the new Advanced Graphing App!
• 2 Special apps (red): the Geometry app and the Spreadsheet app
• 4 Statistics Apps (purple) for descriptive and inferential statistics and data collection
• 4 Solver Apps (orange) for solving specific types of problems (triangles, finance, etc.)
• 3 Explorer Apps (green) for investigating a function’s equation and its graph

You may have bought an HP-41 in EBay, just to find that the battery bay is utterly rusted. There goes your investment! Maybe you wanted it for CL conversion - maybe it was your first 41c and you wanted to see what’s all the fuss about it!

Whatever the reason, letting the rust inside your calculator is a recipe for later disaster. It will corrode the circuit lines, communicate to other parts of the circuit, destroying your investment (and, in the case of the CL, it IS an investment!)

You can easily buy port covers, even battery cover; but it is much more difficult to find this piece in internet. And with a good reason: it is the first thing that fails in the HP41c, and therefore you can only salvage the other parts.

Well, there is an option: you can buy in our shop the adhesive circuit that adapts to the plastic body of the battery connector. It has an extremely strong bonding, and the shape is perfect for the task. I have to say that it is a little difficult to put it properly: you need a firm hand and some experience to do it. I would not recommend to buy one to repair your only calculator, since it will not work properly the first time. At least it did not work for me the first time, but I got the experience of what failed. The second time went well already. So, my advice is: if you want to repair just one calculator, you’ll be better off buying two. If you’re repairing more, then n+1 - so that you can afford one error. Or you may be more skilled than me - in than case buy just as many units as repairs you need to do.

The circuit comes with clear repair instructions, but I would stress the fact that you need to bend it properly to shape beforehand, using the guidelines, and that you should start in the cavity between both ports.

I have used it to repair a calculator that would not start, and that I bought in internet as “for parts”. Now it is my CL. Today I have just repaired a non-working CV - this time keeping the original board in. This will end up in another CL as soon as I receive the new boards, with Sandmath 2x2, among other new features.

Please take a look at the beautiful finish of the battery once repaired.

You can find it here.