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My HP calculator history (I)

First, some story: My first HP calculator was a HP33c in 1980 - when I was 14 and all my class companions were using 4-bangers (those that had a calculator). It was a pleasure to start learning programming: telling a machine what you want it to do...with all of 49 programming steps! You were reaching the limit all the time.

At the same time, I had access to a HP85 computer. Now I see it called a "calculator", but at that time it was considered the very top of professional computing. Apple ][ were considered toys compared with it. It had a decent BASIC language, provision for extended number precision (exponents up to +-499), could run from its ROM without the need of loading an operating system, and it had an integrated mass storage system (256 kbytes magnetic tape) and thermal printer for output. Best of all, it had HP-IB and with it a world of interfacing. In the application we were using it, we were printing invoices with a dot-matrix printer, drawing with an hp 7225A plotter and storing data on floppy discs. Later it came a 5 Mbyte winchester disk ("how on earth are we going to fill it up!"). To add the cream on top, its capacities could be expanded with additional ROMs (up to 6) that could be plugged on a card on the back of the computer.

The manual is absolutely the best computer or calculator manual I have ever seen. Never, ever, HP has approached that level of perfection. It went through all concepts and programming techiques with full details and lots of relevant examples. You can see examples of that manual at It would be an excellent primer for programming for your children.

The keyboard feels a little primitive compared with today's examples, and the machine is clocked at around 650 kHz (meaning kHz, NOT MHz or GHz !!). The basic is interpreted and quite slow. Please remember that this machine is a couple of years older than the first IBM PC. But it was an excellent general purpose machine, best suited to engineering and industry. I have a warm spot in my heart for it since I made my first money writing programs for it.

Nowadays I have an HP85 sample that works flawlessly -except for a clear area in the printhead. The tape machine has been exchanged for a QIC one, with newe tapes, and all the ribbons of the printer have as well been exchanged. The fact that it continues to run after 30 years attests to the quality of HP of yore.

Coming back to calculators...

The HP33c calculator accompanied me up to 3rd term in Engineering - that is, 20-21 years old. Then I moved to a BASIC Casio for the rest of University. This allowed me to do some complex mathematical programming. The BASIC alternative would have been the 71b -but at several times the price of the Casio - but I always was longing for a HP 41c

3 years after I joined an MBA program in Barcelona, and bought an HP19bII. I felt I was betraying the engineering profession by buying a non-programmable, non scientific calculator. I should not have felt that way: it is a fantastic calculator and the solver allows for quite interesting programming. At the time, the alarms and time functions made it quite similar to a personal organizer. The main problem with it was the "real estate" it used on your working table. It was stolen from me, and then I replaced it with an HP 17bII - the original model. I missed the 3 lines display - but it was good enough. I still have that calculator. We were in 1994.

Fast forward to 2006 - after a number of years in finance positions, I enter a general management position, where sin and cos and logs are used, and I am no more money-starved. Then I decided to buy the best there is...the HP 41c - or so I thought...

I bought an HP 41cx, but it appeared that I had passed by a number of exciting calculators for over 15 years: the hp 42s (a 41c+ with an even better form factor) and the hp48 world...I just had to explore it. In a couple of years, I built the collection I now have.

My current preferred calculators are the hp15c and the hp 50g

I use the 50g in my daily work. I can write programs in RPNish RPL (RPL using only the RPN techniques) and the solvers. I use as well the matrix capabilities to manage budgets and company forecasts. I am in business long before my companions have entered the passwords in their Wintel laptops.

I "wear" the 15c in my jacket. It has the right size and format to help me working in the airplane or the high speed train. I have programmed it to add it most of the features of the 12c: date calculations, IRR, NPV, weighted averages, time value of money, etc. It actually is faster to use in most simple applications than the 50g - except when the solver is required. However, programs are extremely slow - when I calculate an IRR, 2 minutes are typical for a 10-year calculation. I guess that I'll have to wait for the hp15c+ (hp15c firmware in a new hp12c hardware)

I could wear the 42s - that I also have. I have developed as well the financial programs that make it similar to the HP17bII - but the solver is not the same as the latter, or the hp 50g for that matter. I prefer the 15c or the 50g - depending on the application.

In a later post, I will discuss in depth these three calculators.
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