I have been using HP calculators since the mid-70’s, when my cousin (who worked for Hewlett-Packard in Sweden) brought an HP-21 to us. When I was in 8th grade and we finally were allowed to use calculators during math class, I purchased the HP-15C, a programmable scientific calculator. In 1987, when I was in high school, the HP-28C was released, and I got it as soon as it came out. The next year I upgraded to the improved HP-28S (32kB instead of 2kB and a 1 MHz processor instead of 640 kHz). Both were clamshell designs. I also got a HP 82240B infrared printer, which used thermal paper.
In April 1990 I was getting the HP-48SX as soon as it came out. I could use the same infrared printer I already had, and I also got an expansion memory card (128 kB, I believe). I used this calculator for many years, and still have it, even if it is not working fully, due to a faulty on/off switch (which seems to be a known issue on these old units). My next project will be to open my calculator and fix this problem…
The HP-48SX had a serial port, built-in Kermit file transfer and infrared communications. There was a large set of programs and utilities available on several bulletin board systems (BBS) and later on the Internet. Most notable were Joe Horn’s Goodies disks. Many programs can be found at hpcalc.org.
Back in the late 1990’s I found some emulators that let me run a HP-48 on my Windows computer. It required a ROM image from the original calculator, which I of course still had. Then in 2000, HP released the ROM images for free downloads. Very cool!
The emulators have evolved, and now everyone can get a HP48SX, or it’s successors 48G and 48GX, on their desktop. It is actually very simple. You just need three small downloads to do this:
* AHP-48SX ROM image
Simply unpack the Emu48 installer and run it. Put the ROM image in the Emu48 directory and use the convert.exe program to convert the ROM image. Then copy the files for the skin into the same directory. Launch the program, and you have a really cool calculator. Everything works, including programming! More skins, as well as other programs, can be found at hpcalc.org.
HP calculators, with the exception of the business models (designated by a B in the model name) use Reverse Polish Notation (RPN). It is a faster and better way to calculate, especially more complex computations, but can be confusing to non-engineers/technical users. I highly recommend to learn this, though.
So go get this calculator for your computer and start playing!