RS-232 voltage conversion should be easy. Most people sort of faked the full levels and got it working anyway. If memory serves, the calculator itself has a built-in mode, where it will start spewing bits out that mini-connector, so you might not need a lot of special softwarre from 1989 to get things going. The manual should have details.
Kind of amazing that 2025 cells have been around that long...
@Ssidman... "Came with a kind of serial interface to back stuff up on your (DOS) PC"
I saw that in the manual. I have the cable (think a 2.5 mm stereo jack connector) but not the box that went with it, or the software. But it probably just needs a convertor circuit to get the voltages up to RS-232, I might be able to figure that out.
Speaking of calculator accuracy, see http://www.rskey.org/~mwsebastian/miscprj/results.htm for the range of accuracies in calculators. I think the trig functions on most of those things were CORDIC.
I actually had that Casio organizer, back in the day. Came with a kind of serial interface to back stuff up on your (DOS) PC. If you have the whole kit, and can get that one running again, a simple examination of the saved file should answer questions on compression techniques.
Thanks all for the comments and info. I was not sure if anyone would be interested in old stuff like this, but I will try and get this one going and report further.
@Traneus...I remember seriously wanting an HP-95 when they came out. I seem to remember you could get a couple of add-on things for them (maybe a floppy drive??)
I have a couple of other ancient devices.... an old Palm, which apart from bigger Memory does not do much more than this, and an HP Jornada which is more like the HP-95 - it runs a crude windows OS and can be linked to a PC. I guess the main thing in this connected age is that these things either don't connect - they are standalone - or they only have rudimentary commuunications with a PC. If you've used an Ipad or smartphone you'd find them very limiting.
I'm too young to have enjoyed these in the late 80s, but was using their distant relatives by the mid to late 90s before Palm Pilots and WinCE PDA really took off or at least were affordable on my college budget. I remember one boss that had one of those Psion devices...man were they the cat's meow at the time.
My first unit was a Royal DM80Plus Personal Organizer with merely 11K. It was attrocious, data entry being a major pain. I quickly moved to the TI in the subject line. This little beauty had a RS232 docking station for syncing with a PC, thus enabling me to keep CSV files with wiring/network/equipment details for pretty much everyone in the company. Having this at my fingertips when away from my desk, since no one in the computer department but the boss got laptops at the time, was a godsend for fixing problems.
I use an HP95 (vintage 1990) pocket MS-DOS PC for writing on camping trips where I don't have access to chargers. The HP95 runs for more than a week from a pair of alkaline AA cells. It stores a standard FAT filesystem image on internal SRAM (C: drive) and on a removeable PCMCIA SRAM card (A: drive). MS-DOS, Lotus 1-2-3 spreadsheet, a simple text editor, and a few other programs are stored in masked ROM. The HP95 and the SRAM card both have coin cells for SRAM backup power.
I copy the files from the SRAM card onto a Linux box when I return home.
@Max:But didn't you hear about the classic problem with the trig functions on Casio FX-850P Personal Computer ...LOL
Not that I recall but my calculations using the Casio were far more accurate than the surveyors, so much so he relied on me to produce the results for him on a few occasions, which I'm quite proud of being Math's isn't my strong point and it was his trade.