jmbh Calculator Collection

My first calculator a TI 57 programmable, was bought when I was in university in about 1975 and we were inseperable. Up until then I used a slide rule. I wasted many hours playing lunar lander. Of course it had volatile memory so that I had to re-enter the program every time I turned it back on. Of course what I really wanted was the HP 65 but it was way out of my price range being US$795 and me being on a modest $35 a week university scolarship.

This site will outline my aquisitions and losses with details about each of the calculators and associated peripherals I owned, up until the present day. The pages below provide details and information on each of these calculators with interesting information. 

My history with calculators

HP 41C

After I left Uni in 1976 I took a break from study and resumed again in 1979. At that stage I still had my TI 57 I longed for something more powerful. During the period which I had the TI 57 I got into the habit of documenting my programs. I used a standard program chart on which I listed the instructions and comments againse each line of code. I also created a small quick reference a little larger than a business card on which there was a table specifying the ooperating instructions for each program. I used to cary the cards around with the calculator and the programs I kept in a small folder. I used this for many years, even after I left college.

I had been on the look out for an HP 41C and in about 1982 my wife saw one at an Evans and Clarke auction. It included the thermal printer, card reader, some cards and the origonal manuals and we managed to score it for $250, which by any standard was a bargain.

I then used it for my Associate Diploma in Electronics engineering which I was studying at the time. I got to know it very well and wrote many programs for it many of which I still have on cards. Unfortunately it was stolen in 1976 (I think) nut after my next calculator purchase.

HP 15C

My next purchase was the HP 15C. This calculator I have to say was perfect for electronics. I love the form factor being landscape rather than the traditional portrait. I also loved the powerful engineering features. Studying electronics the complex arethmetic and matrix calculations and the other powerful functions made it a dream. Unfortunately that was also stolen in 1985 at my last year in college. I then went back to the 41C. For general use my favourite calculator was the HP 15C, simply due to its layout and powerful engineering features. 


The HP 41C was covered by insurance which funded my next purchase, an HP 41CX, a new HP 82104A card reader (the origonal was stolen along with the calculator) and a stack of magnetic cards and card wallets. I had left college by that time but one of my friends who was still at college knew soneone who worked at HP and they could purchase HP calculators at a significant discount. My friend was arrainging to buy a number of calculators though the HP employee. I saved about $200 to $250 on new and together with the insurance money I was only out of pocket a couple of hundred dollars. 

Miscellaneous Calculators

Over the years I hacve aquired several other HP calculators. 

I bought the HP 48G second hand for a modest sum, cannot remember where or when. I used it as my principal calculator for several years. I quite like this calculator but it has now been replaced by the HP 35s calculator.

I bought an HP 32SII calculator for the wife and she has now destroyed her second but it has seen a lot of use and abuse. The middle row of keys are faulty and since it is too expensicve to replce it will probably be relegated to the museum. Given tht there are excellent emulators on the iPhone 

I also bought an HP 35S calculator at some point and I quite like the look and style of it. It is now my go-to calculator.

On a whim I also bought an HP 6S but I do not use it. I have it for curiosity's sake. 


I aquired an HP Palm Top HP95LX in box with manuals in the early 00s that someone was throwing out. It is in perfect working order except that it indicates low battery with fresh batteries. It was there when I aquired it but I have not botheres to fix it since it does not affect the operation. I just have to remember to replace the batteries before they get too low.

It is useful if a serial terminal is required since it has a standard RS 232-c port with inbuilt terminal program. 

It also has a basic scientific calculator with an equation solver.

Synthetic Programing

It was at this time I discovered synthetic programing. This is specific to the HP 41 series calculators and allows the user to access many undocumented features of the calculator. It allows functions and features that are not available though notmal operation and can reduce the size of programs considerably as well. I spend many many unproductive hours investigating and programming using synthetic programming. 

My third HP 41 series calculator came from a Salvo Op Shop. It was an HP 41C with a number of modules, a card reader and printer for $20, all in working order.

My last HP 41C was from a collegue which again included the card reader and printer. However the calculator was faulty and to this day does not work. The printer was missing the small plastic window in front of the outfeed and appeared to be in poor condition.


All of my calculators have been in storage since I moved in 2011 and my HP 41CX had leaky batteries. I cleaned up most of the corrosion and leaked chamicals and the calculator works but the ports do not work properly and the battery contact membrane is quite damaged. I wil buy a replacement membrane and fit it. The working HP 41C is now not working even though its batteries did not leak. I will pull it apart and give the battery contacts and contacts a good clean with IPA to see if that fixes it. I may also have a look at the other non-working HP 41C to see if I can get it to work or perform some diagnostics.

I have already refurbished one of the printer batteries and one printer seems to work but it is difficult to tell with faulty I/O ports. The other printer has a slipery feed roller so I will try to repair that printer. The third printer is most probably parts only but I will see if it can be repaired.

The card readers all have sticky feed rollers but I have silicone replacements so they sould be easily repairable.