Reverse Polish Notation - HP 48G

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lschiavo

This space for rent.
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If the title made any sense to you, you are a huge geek:mug:

I just dug mine up and it still works! I still love the unit conversions...might be handy on a brewday?

I searched and see you can still buy these for about 200 big-uns. Make me an offer:)

GEEK PORN:

41K7FGH6RDL.jpg
 
I still have (and use) my HP42S. Love the RPN. But the one I really like to use is the one in my avatar - Ricoh 151 slide rule. That, and my 27 rod soroban (Japanese style abacus). Yeah, I'm old school!
 
I still have (and use) my HP42S. Love the RPN. But the one I really like to use is the one in my avatar - Ricoh 151 slide rule. That, and my 27 rod soroban (Japanese style abacus). Yeah, I'm old school!

I never had the 42S but I have seen plenty of them. Why not still use it? It, like the GP is a tank. I actually should have two slide rules (dad's and grandpa's). I need to figure out the slide rule...I was never taught (I'm only 40). If I can find them, that is my next project.
 
I never had the 42S but I have seen plenty of them. Why not still use it? It, like the GP is a tank. I actually should have two slide rules (dad's and grandpa's). I need to figure out the slide rule...I was never taught (I'm only 40). If I can find them, that is my next project.

I used a slide rule in college (MEE in '69) and for the first few years on the job. I bought a HP-45 in '73; put my Post Versalog slide rule in a drawer and didn't look at it again until an article about slide rules was published in Scientific American in (IIRC) 2006. Got interested and started collecting them - bought a bunch on eBay (got to be careful there, though, because many are missing the cursor, or screws, or have the owner's name scratched into the rule). I've got somewhere over 100 slide rules now. :rockin: If you get one, there are a lot of books and manuals available on line, and there are some on-line emulated slide rules that you can play with (search for virtual slide rules).

http://www.sliderulemuseum.com/ (click the "Slide Rule Library, Manuals & Books" button)

For books, I recommend "The Slide Rule" by Lee Johnson at the above site.

The Post Versalog manual is good, too, though oriented toward that particular slide rule.

And there is a yahoo group list - the International Slide Rule Group for discussions about slide rules. Also the Oughtred Society ($35/year) which puts out a nice journal (2 issues/year), mostly oriented toward collectors.
 
I forgot to mention that I use my slide rule in brewing, too. It's really useful to calculate your post boil gravity and volume given the pre boil gravity and volume. For example, if I have 6.9 gallons at 1.042 preboil, I just set the cursor hairline to 4.2 on the D scale, move the slide to set 6.9 on the CI scale under the hairline, then I can just move the cursor to any desired volume on CI to find the post boil gravity, or conversely move the cursor to any desired post boil gravity on D and read the necessary boiled down volume on CI. I can see at a glance that 6.25 gallons = 1.0464, 6 gallons = 1.0483, 5.5 gallons = 1.0527, etc.
 
I've got that HP48 and an HP28S sitting next to me right now. I use the 28 almost every day. RPN is the only kind of calculator I'm comfortable with. And, I must have an endless stack. I can't stand using a calculator that isn't RPN with an argument stack.

HP-28S-3-S.JPG
 
That's good stuff there DeafSmith. I've got some study ahead.

What battery would you recommend for the slide rule? If I find the heirlooms, I'm sure I'll need new batteries;)
 
Ha, ha! My wife used to do HP tech support and she has a box full of calculators. She still had to buy a new one for her accounting statistics course, because the textbook and instructor assumed you had a specific calculator.
 
I just use my fingers and and sometimes my toes:D

Actually, in college (70s-80s) I had an HP that allowed you to store formulas and stuff on 1 inch long tapes that you slid into the unit. You could do simple programming with it too. A lot of people were using them to cheat on exams, so they got banned. I can't remember the model. Anyone ever use on of these?
 
I've got that HP48 and an HP28S sitting next to me right now. I use the 28 almost every day. RPN is the only kind of calculator I'm comfortable with. And, I must have an endless stack. I can't stand using a calculator that isn't RPN with an argument stack.

HP-28S-3-S.JPG

I have not seen that 28S but I like it. I bet the hinge is a weakness. There's gotta be some sort of ribbon cable in there. Well, you have the 48G to back you up:)

Now that I found it, My 48G is going on my desk. I've been using a radio shack solar for years. I usually only add and subtract in my line of work but who wouldn't miss a cube root at your fingertips?
 
I have not seen that 28S but I like it. I bet the hinge is a weakness. There's gotta be some sort of ribbon cable in there. Well, you have the 48G to back you up:)

Yea, you'd think the connection between the two halves would be a weakness, but never. I've been using this thing almost continuously since 1988 when I bought it ($180!).
 
I have not seen that 28S but I like it. I bet the hinge is a weakness. There's gotta be some sort of ribbon cable in there. Well, you have the 48G to back you up:)

Now that I found it, My 48G is going on my desk. I've been using a radio shack solar for years. I usually only add and subtract in my line of work but who wouldn't miss a cube root at your fingertips?

If you need to add and subtract, you'll need an abacus (Chinese suan-pan or my preference, the Japanese soroban) because you can't add and subtract on the slide rule. But with a log-log type slide rule, you can multiply, divide, take squares and square roots, cubes and cube roots, do trigonometry - solve triangles, raise any number to any power or take any root of any number, solve proportion problems, etc.
 
If you need to add and subtract, you'll need an abacus (Chinese suan-pan or my preference, the Japanese soroban) because you can't add and subtract on the slide rule. But with a log-log type slide rule, you can multiply, divide, take squares and square roots, cubes and cube roots, do trigonometry - solve triangles, raise any number to any power or take any root of any number, solve proportion problems, etc.

You would be a fabulous slide rule salesman.
 
... a pocket calculator is smaller and lighter.

Yeah, but where's the fun in that? :D And what do you do when the batteries run out? :)

Seriously, I think it would be a good idea to teach kids in school to use the slide rule. They'd come out with a much better feel for numbers and they'd learn to mentally check that an answer they got from their electronic calculator was "reasonable", instead of just punching numbers into the calculator and believing whatever comes out. They'd also learn that when you do a calculation with three digit numbers, the answer that comes out of the calculator isn't accurate to the ten significant digits displayed.
 
... a pocket calculator is smaller and lighter./QUOTE]

Yeah, but where's the fun in that? :D And what do you do when the batteries run out? :)

Seriously, I think it would be a good idea to teach kids in school to use the slide rule. They'd come out with a much better feel for numbers and they'd learn to mentally check that an answer they got from their electronic calculator was "reasonable", instead of just punching numbers into the calculator and believing whatever comes out. They'd also learn that when you do a calculation with three digit numbers, the answer that comes out of the calculator isn't accurate to the ten significant digits displayed.

I've got a nice wooden K&E here. It was my dad's. I learned how to use a couple of the scales on it, but looking at it now I can't remember. It's great for scratching tween my shoulderblades.
 
Just got to post to this thread! I bought my HP37E in 1983 because I didn't want a calculator that would break down during my final exams. I'm still using it in the brewery, and it's on it's fourth set of batteries.
 
Just got to post to this thread! I bought my HP37E in 1983 because I didn't want a calculator that would break down during my final exams. I'm still using it in the brewery, and it's on it's fourth set of batteries.

That's cool! Someone needs to program their old HP to control their brewery. I could change channels with mine back in the day.
 
My old HP45 was stolen many years ago. I remember there was an undocumented timer function - you pressed a certain combination of keys and the display would start counting (every second?). I wonder if there are undocumented functions in some of these other HP's?
 
All of the left-handed engineers I know use RPN calculators. I never got the hang of it. Don't quite understand the concept. A friend of mine once said that it's the natural way of thinking. I must be unnatural.

You can download emulators for your phone and computer.

I do have a slide rule, though. It came with a holster. Bought it at a yard sale.
 
That's cool! Someone needs to program their old HP to control their brewery.

Now THAT would be cool. The 37E is not programmable but I *can* calculate the net present value of all the beer I am going to brew for the next 20 years. ;-)
 
My old HP45 was stolen many years ago. I remember there was an undocumented timer function - you pressed a certain combination of keys and the display would start counting (every second?). I wonder if there are undocumented functions in some of these other HP's?

The 48G had a version of minesweeper on it.
 
RPL's use in the calculator was that it is a way that you can do algebraic calculations that have sub-calculations in the formula without having to use parentheses by using the "enter" key first, then again whenever you reach a point were the sub-calculation is. Enter made the value an X and the next entry became the Y. Pretty easy once you get the hang of it.
 
I think I have a 48g or gx and a 49 somewhere. I need to find them both if they are worth some money.
 
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