Cheers Warren - and thanks so much for the offer, but I'm only really collecting RPN calculator stuff. I really appreciate the offer though!!
Simon - I now have nine HP's in various flavours. Nowhere enough. LOL! I'm on to http://www.hpmuseum.org/ and have put a few posts up asking whether anyone has a rare HP-10C for sale. Hmm... rare..... (Homer-style throat gurgle effects).
Cheers Warren - and thanks so much for the offer, but I'm only really collecting RPN calculator stuff. I really appreciate the offer though!!
Simon - I now have nine HP's in various flavours. Nowhere enough. LOL! I'm on to http://www.hpmuseum.org/ and have put a few posts up asking whether anyone has a rare HP-10C for sale. Hmm... rare..... (Homer-style throat gurgle effects).
Forgive my ignorance but as a non aware non calculator collecter what is RPN.
Forgive my ignorance but as a non aware non calculator collecter what is RPN.
Essentially - there's no "equals" key.
I, and many others, find that RPN, or "Reverse Polish Notation" is a more fluid and efficient way of keying in your queries than in algegraic mode, which most calculators use.
For instance, to add "15" and "25" on an algebraic calculator you'd hit the following sequence:
"15", "+", "25", "=" and get your answer "40".
On an RPN calculator you do this:
"15", "ENTER", "25", "+" - and on hitting the plus key you get your answer, 40.
15 is entered by you, and when you hit "ENTER", it's loaded into a "stack" above the display register. Then you type 25 and press the plus key. The plus key triggers an addition between what's currently showing (i.e. 25) and the number stored in the stack register above it. Beautiful!
For an equation (15+25)x(34-6) you'd key:
"15", "ENTER", "25", "+", "34", "ENTER", "6"", "-", "x" and on hitting the final "x" you'd get 1,120, your answer by multiplying the results of the two equations that you solved along the way already. You just start on the left and go straight across. The beauty of it is that you get to see intermediate results as you go as they move up and down within the stack registers. Each set of parentheses is solved in order and then the operands keyed in between them finalise the result.
Yep the emulators are FULLY functional - programming abilities, registers, the lot. HP actually sell a fully-functional "soft" HP-12C for the iPhone as a real calculator model - albeit cheaper than the hardware version, of course. The screen resolution of the iPhone (160dpi) is well-good enough for it to be a pleasure to use. Crystal clear.
I can't see anything to the right of the on/off switch. I will send it up to you in the next couple of days. Same deal as before. I will leave it alone and send it up as is.
I just did a scan of what is left of all the old hard drives in my head and figured out it is not my original HP-35. It was given to me a very long time ago and was just left in a drawer in my desk as I then had the later models with more features. It ended up in a box with other stuff you collect after working at the same place for thirty years. I was looking for something else and was amazed to find it. I have no idea whether it works. I will leave that for you to figure out Chris.
The HP-35 was HP's first pocket calculator. It was introduced at a time when most calculators (including expensive desktop models) had only the four basic functions. The HP-35 was the first pocket calculator with transcendental functions and the first with RPN.
Based on marketing studies done at the time, the HP-9100 was the "right" size and price for a scientific calculator. The studies showed little or no interest in a pocket device. However Bill Hewlett thought differently. He began the development of a "shirt pocket-sized HP-9100" on an accelerated schedule. It was a risky project involving several immature technologies. HP originally developed the HP-35 for internal use and then decided to try selling it. Based on a marketing study, it was believed that they might sell 50,000 units. It turned out that the marketing study was wrong by an order of magnitude. Within the first few months they received orders exceeding their guess as to the total market size. General Electric alone placed an order for 20,000 units. As a result, they later had to warn people to expect waiting lists in the Hewlett-Packard Journal. This was an unusual situation for HP. While many companies advertised calculators months or even years before you could buy one, HPs were normally available the day the first advertisements appeared.
The early versions said only "Hewlett Packard" on the faceplate and inside HP the product was simply called "The Calculator". Bill Hewlett suggested naming it the HP-35 because it had 35 keys. Later as HP developed more models, "35" was added to the faceplate. The HP-35 and probably the entire HP pocket calculator product line was the sole result of a visionary CEO who chose to ignore the market studies and produce what he felt that engineers would want. His view of the market was that if the engineer at the next bench liked it and thought it would make his job easier, then it was worth doing. The HP-35 was developed in two years, at a cost of approximately one million dollars with twenty engineers. At the time, three to five years was a typical HP development cycle.
The early HP's were built tough and built to be repaired. After removing about a dozen screws you can get to anything in the HP-35.
At the time, many of the companies producing calculators could build adequate circuits and firmware, but didn't have the experience or facilities to make a well designed housing, keyboard, and display. Many of these brand-X machines were very failure-prone and quite crude in design.
By contrast, the packaging of the HP-35 was of major importance. Its size, looks, keyboard, and display were all carefully thought out. The keyboard is divided into groups with different sizes, color and placement of nomenclature. Even differing amounts of contrast were used to separate groups. (The most used groups had the greatest contrast level.) The keys were made in a double mold process with the legends going all the way through the keys so they could never wear off. The keyboard panel used an HP-developed spring contact which is essentially unchanged in current calculators.
The HP-35, like all the hand-held HPs that followed, was required to remain undamaged after falling three feet onto concrete on each of its corners. The case had sculpted sides, such that the top caught the light and the bottom was in shadow making the calculator look thinner than it really was. All screws were hidden.
The HP-35 had numerical algorithms that exceeded the precision of most mainframe computers at the time. During development, Dave Cochran, who was in charge of the algorithms, tried to use a Burroughs B5500 to validate the results of the HP-35 but instead found too little precision in the former to continue. IBM mainframes also didn't measure up. This forced time-consuming manual comparisons of results to mathematical tables. A few bugs got through this process. For example: 2.02 ln ex resulted in 2 rather than 2.02. When the bug was discovered, HP had already sold 25,000 units which was a huge volume for the company. In a meeting, Dave Packard asked what they were going to do about the units already in the field and someone in the crowd said "Don't tell?" At this Packard's pencil snapped and he said: "Who said that? We're going to tell everyone and offer them, a replacement. It would be better to never make a dime of profit than to have a product out there with a problem". It turns out that less than a quarter of the units were returned. Most people preferred to keep their buggy calculator and the notice from HP offering the replacement.
Omaroo, i have a sore head thinking about trying to use your RPN calculators I have an addiction to collecting old telescopes and brass microscopes. Mark
Bert (avandonk) has done it again and sent me a rather historic calculator for my HP Calulator Museum - the original (i.e. very first) handheld calculator - and it utilised RPN from the outset.
I'd really like to thank Bert for allowing me to restore to working order a significant piece of electronics history which is nearly 37 years old.
You have done a great job of restoration there Chris. It just occured to me that thankfully I started 'collecting' HP calculators before you, otherwise you would not have them now.
I spent many hours using all three before computers were practical. It was easier and far more accurate to do calculations with a HP than sit down and write the machine code as memory was very limited in those days. Ever tried to use a DEC PDP8 with 2k of memory?
It gives me a lot of satisfaction that they are in better condition and in safer hands now. The fact that in your capable hands they are working as well is a real bonus!
My ex wives used to tell me off for never throwing anything out. Seems like they were the only ones that were.
Yes, RPN is great - I love using my HP48GX. I have had it for over 14 years, and it has never missed a beat. I do quite a lot of programming with it - again I love doing that. I also have the infra red printer for it so can print out all my programmes. Also all the programming manuals.
Nobody has mentioned the HP48GX. Why? Is it too "modern"?
............ Planet images....
I really appreciate the offer though!! 
- I love using my HP48GX. 
