There was a time when being an engineering student meant you had a sword. Well, really it was a slide rule hanging from your belt, but it sounds cooler to call it a sword. The slide rule sword gave way to calculators hanging from your belt loop, and for many engineers that calculator was from HP. Today’s students are more likely to have a TI or Casio calculator, but HP is still in there with the HP Prime. It is hard to call it a calculator since the latest variant has a 528 MHz ARM Cortex A7, 256 MB of RAM, and 512 MB of ROM. But if you can’t justify a $150 calculator, there are some cheap and even free options out there to get the experience. To start with, HP has a free app that runs on Windows or Mac that works just like the calculator. Of course, that’s free as in no charge, not free as in open source. But still, it will run under Wine with no more than the usual amount of coaxing.
You might wonder why you need a calculator on your computer, and perhaps you don’t. However, the HP Prime isn’t just your 1980s vintage calculator. It also has an amazing number of applications including a complete symbolic math system based on xCAS/Giac. It is also programmable using a special HP language that is sort of like Basic or Pascal. Other applications include plotting, statistics, solvers, and even a spreadsheet that can hold up to 10,000 rows and 676 columns.
It is easy to think that HP provides the free PC software so you’ll go out and buy the real calculator, and that may be part of it. However, you can also get official apps for Android and iOS. They aren’t free, but they are relatively inexpensive. On iOS the cost right now is $25 and on Android it is $20. There are also “lite” versions that are free.
It appears that these apps are not emulating the actual calculator hardware, but are ports of the calculator code. So this isn’t a case of someone just writing a pretend calculator, these apps act like the real calculator because it is running the same source code. For example, there is an application, HP Connectivity Kit, that lets you talk to a real calculator over the network. The PC and phone versions will also connect just like a real device.
You can write programs on the device or if you have the HP Connectivity software (also free) you can write programs on your PC. You can even find some from the Internet. If you miss your old calculator, there is a define feature that lets you program like a key macro recording.
The programming language isn’t hard to pick up. Here’s a short snippet:
EXPORT AREAVOL() BEGIN LOCAL N1, N2, L1; CHOOSE(N1, "Area or Volume?", "Area", "Volume"); IF N1 == 1 THEN CHOOSE(N2, "Choose shape", "Rectangle", "Triangle", "Disk"); ELSE CHOOSE(N2, "Choose solid", "Prism", "Cylinder", "Cone", "Pyramid", "Sphere"); . . .
You’d think that the real hardware would be a prime platform for hacking, but so far that’s still on the to-do list. The only really good hardware hack for the real calculator adds a Samsung battery with a higher capacity to the machine. There are also some enticing pads on the PCB that appear to support a buzzer and I2C communications, but there’s no firmware for it. There have been a few attempts to load alien firmware into the device, but there’s no full-blown development system. Getting to the JTAG port looks pretty intense. There’s also been the inevitable hacking of the communication protocol.
History is replete with products that seemed amazing for their day but turned out to be just a stopgap for something better. Cassettes gave way to CDs and then CDs gave way to digital music. Telephone answering machines gave way to voicemail. Calculators have that feel to them. How much longer will we need them? Are the virtual HP Prime applications going to overshadow the physical device?
Regardless, the Prime is state of the art and would shame a personal computer from a few years ago. You can only wonder if it will be the last great calculator, or if there are more yet to come. And a calculator still makes a nice project. Not all homemade calculators are simple.