HP Calculators with native CF temperature conversion

02102024, 11:25 AM
Post: #1




HP Calculators with native CF temperature conversion
Is the HP55 the only pre80s calculator that does C>F/F>C temperature conversions natively?
Could the HP41 (or any other model) made to have this conversion with an addon module? Thanks. 

02102024, 12:25 PM
Post: #2




RE: HP Calculators with native CF temperature conversion
(02102024 11:25 AM)calccalcs Wrote: Is the HP55 the only pre80s calculator that does C>F/F>C temperature conversions natively? Yes to both questions. In the case of the HP41C, addon modules (especially custom ones) can add many many new features, as long as these features can realisticly (speedwise) run on the 41C. Namir 

02102024, 01:39 PM
Post: #3




RE: HP Calculators with native CF temperature conversion
For the HP41 family, I'm pretty sure both the Petroleum and Thermal & Transport Science Pac ROMs included these, plus other related conversions.
Bob Prosperi 

02102024, 02:34 PM
Post: #4




RE: HP Calculators with native CF temperature conversion
(02102024 11:25 AM)calccalcs Wrote: Is the HP55 the only pre80s calculator that does C>F/F>C temperature conversions natively?I used to use statistics for this: enter three known quantities for degrees C and the degrees F equivalents (40, 40; 0, 32; 100, 212) in the statistics X and Y sum registers, and use the resulting trend line to get the answer given for any input. I did this on the HP25, my first HP calculator. Sorry I don’t recall the exact steps, but it has been a few years (decades (not quite half a century)). Not exactly what you were asking for, but it did bring back a happy memory for me. 

02102024, 02:40 PM
(This post was last modified: 02102024 04:55 PM by C.Ret.)
Post: #5




RE: HP Calculators with native CF temperature conversion
(02102024 11:25 AM)calccalcs Wrote: Is the HP55 the only pre80s calculator that does C>F/F>C temperature conversions natively?No. There certainly where a few other calculators that does °C↔°F conversion at the time. I'm far from knowing them all. But, for example, the Texas Instruments Ti59 or Ti58 were all available with the Main Library solid state module which ML25 Unit Conversion (2) program allows volume, weight and temperature conversions. (02102024 11:25 AM)calccalcs Wrote: Could the HP41 (or any other model) made to have this conversion with an addon module?Yes, most definitely and also without any addon module as well. Like all programmable calculators of this era. The highend calculators of the time were programmable to meet the specific needs of their users. Temperature conversions are a typical example of use. These conversions can simply be programmed directly into these machines. What's special about the HP41 is that with a few instructions a program can be composed to offer all conversions between degrees Kelvin, Fahrenheit and Celcius in a userfriendly and intuitive environment: 001 LBL"TCONV" 002 273.15 STO 00 SF 27 "A:.F B:.K C:.C" PROMPT 007 LBL A FC?C 22 XEQ 01 XEQ 00 SF 01 STO 01 FIX 1 "F" XEQ 10 016 LBL B FC?C 22 XEQ 02 XEQ 00 SF 02 STO 02 FIX 2 "K" XEQ 10 025 LBL C FC?C 22 XEQ 03 XEQ 00 SF 03 STO 03 FIX 1 "C" XEQ 10 GTO A 035 LBL 00 CF 01 CF 02 CF 03 RTN 040 LBL 01 FC?C 02 XEQ 02 RCL 00  9 * 5 / 32 + RTN 052 LBL 02 FC?C 03 XEQ 03 RCL 00 + RTN 058 LBL 03 FC?C 01 XEQ 01 32 – 5 * 9 / RTN 068 LBL 10 ASTO L CLA ARCL X "~ ." ARCL L FIX 4 PROMPT CF 22 077 END Usage: Initialize the program by executing XEQ “TCONV” Enter a temperature and press A, B or C to indicate respectively whether it is Fahrenheit, Kelvin or Celsius. To convert the displayed temperature, press A, B or C (without entering a value) to obtain °F, °K or °C respectively. The displayed temperatures are stored in registers R01, R02 and R03 depending on whether they are °F, °K or °C. The result of the conversion is in the X register. The ALPHA register gives the rounded value followed by its unit. Pressing R/S key cycle through the three units. Ultimately this is how I like to have the conversions on my HP41. Don't hesitate to create your own method. This is the main purpose of the HP41 which is designed to be customized by the user. If you don't believe me, just have a look under the display at the message written on the four largest keys this machine has: ON any USER press the PRGM is ALPHA. 

02102024, 06:26 PM
(This post was last modified: 02102024 06:29 PM by Thomas Klemm.)
Post: #6




RE: HP Calculators with native CF temperature conversion
(02102024 02:34 PM)DGM Wrote: I used to use statistics for this: enter three known quantities for degrees C and the degrees F equivalents (40, 40; 0, 32; 100, 212) in the statistics X and Y sum registers, and use the resulting trend line to get the answer given for any input. I did this on the HP25, my first HP calculator. Sorry I don’t recall the exact steps, but it has been a few years (decades (not quite half a century)). The HP25 hasn't linear regression builtin. You either used a different model or wrote a program similar to this: Code: PROG Example Insert data: CLEAR REG 40 ENTER Σ+ 32 ENTER 0 Σ+ Calculate parameters: GTO 03 R/S The parameters \(a\) and \(b\) can now be found in registers 1 and 2: RCL 1 1.80 RCL 2 32.00 Celsius to Fahrenheit: 37 GTO 01 R/S 98.60 Fahrenheit to Celsius: 451 GTO 02 R/S 232.78 How does it work? For just two points \(P_1 = (x_1, y_1)\) and \(P_2 = (x_2, y_2)\) we want to solve the following linear system of equations: \( \begin{bmatrix} x_1 & 1 \\ x_2 & 1 \\ \end{bmatrix} \cdot \begin{bmatrix} a \\ b \\ \end{bmatrix} = \begin{bmatrix} y_1 \\ y_2 \\ \end{bmatrix} \) This leads to: \( \begin{align} a &= \frac{y_1  y_2}{x_1  x_2} \\ \\ b &= \frac{x_1 y_2  x_2 y_1}{x_1  x_2} \\ \end{align} \) However we solve instead the following system of equations: \( \begin{bmatrix} \sum x^2 & \sum x \\ \sum x & n \\ \end{bmatrix} \cdot \begin{bmatrix} a \\ b \\ \end{bmatrix} = \begin{bmatrix} \sum xy \\ \sum y \\ \end{bmatrix} \) In case of \(n = 2\) the solutions are: \( \begin{align} a &= \frac{2(x_1 y_1 + x_2 y_2)  (x_1 + x_2)(y_1 + y_2)}{2 (x_1^2 + x_2^2)  (x_1 + x_2)^2} \\ &= \frac{(x_1  x_2)(y_1  y_2)}{(x_1  x_2)^2} \\ &= \frac{y_1  y_2}{x_1  x_2} \\ \\ b &= \frac{(x_1^2 + x_2^2)(y_1 + y_2)  (x_1 + x_2)(x_1 y_1 + x_2 y_2)}{2 (x_1^2 + x_2^2)  (x_1 + x_2)^2} \\ &= \frac{(x_1  x_2)(x_1 y_2  x_2 y_1)}{(x_1  x_2)^2} \\ &= \frac{x_1 y_2  x_2 y_1}{x_1  x_2} \\ \end{align} \) Thus, we end up with the same result. References 

02102024, 07:07 PM
Post: #7




RE: HP Calculators with native CF temperature conversion
Seems easier to just remember the 9/5 conversion factor and key in a tiny program to carry it out.


02102024, 08:02 PM
Post: #8




RE: HP Calculators with native CF temperature conversion
(02102024 07:07 PM)Dave Britten Wrote: Seems easier to just remember the 9/5 conversion factor and key in a tiny program to carry it out. But what if you are an eccentric professor of numerical analysis who wakes up one morning and feels feverish? (…) So tossing both thermometers into a sink of lukewarm water, he reads the following pairs of temperatures as the water cools: \( \begin{array}{ccccccc} \hline n & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline C & 40.5 & 38.6 & 37.9 & 36.2 & 35.1 & 34.6 \\ \hline F & 104.5 & 102 & 100 & 97.5 & 95.5 & 94 \\ \hline \end{array} \) Suppose the professor puts the centigrade thermometer in his mouth and finds he has a temperature of 37°C. Should he be worried? Insert data: CLEAR REG 104.5 ENTER 40.5 Σ+ 102 ENTER 38.6 Σ+ 100 ENTER 37.9 Σ+ 97.5 ENTER 36.2 Σ+ 95.5 ENTER 35.1 Σ+ 94 ENTER 34.6 Σ+ Calculate parameters: GTO 03 R/S The parameters \(a\) and \(b\) can now be found in registers 1 and 2: RCL 1 1.76 RCL 2 33.53 Celsius to Fahrenheit: 37 GTO 01 R/S 98.65 It looks like he is safe. This example is from HP25 Applications Programs: CHAPTER 6 STATISTICS CURVE FITTING—LINEAR REGRESSION I had to chuckle when I read this: Quote:This thermometer, however, will not fit comfortably into his mouth. Still, with some ingenuity.... I assume that they had a good time writing these manuals. 

02102024, 08:03 PM
Post: #9




RE: HP Calculators with native CF temperature conversion  
02112024, 01:25 AM
Post: #10




RE: HP Calculators with native CF temperature conversion
On the 41 I just have a short program and have key assignments for the functions.
http://WilsonMinesCo.com (Lots of HP41 links at the bottom of the links page, http://wilsonminesco.com/links.html ) 

02112024, 06:36 AM
(This post was last modified: 02112024 10:14 AM by C.Ret.)
Post: #11




RE: HP Calculators with native CF temperature conversion
(02112024 01:25 AM)Garth Wilson Wrote: On the 41 I just have a short program and have key assignments for the functions. This is the path of reason and generally speaking a very good practice. Especially if you only need to convert temperatures between the two scales °F and °C. 001 LBL "C2F" 1.8 * 32 + END ASN "C2F" 64 001 LBL "F2C" 32  1.8 / END ASN "F2C" 63 Now in USER mode you have °F←°C conversion on SHIFT6 key (same key combinaison as the HP55) instead of rectangular to polar R→P conversion. And since, there is no 'g' shift key on HP41, °F→°C conversion is set on SHIFT5 key instead of polar to rectangular P→R conversion. As I pointed out in my previous post, the HP41 is the most versatile programmable calculator of this era. It is easy to configure to the user's exact needs by the user himself, as long as he understands the operating principles or has the excellent instructions booklet on hand. EDIT: Very proud of my last code, I have just lent my HP41C to my eldest son (26 years old) who grimaced while using this surprising portable device. He also laughed when he saw the code. However, he made two relevant remarks which led us to correct my first version together. He was very surprised by the disconcerting ways he has to follow to modify the code while using only the rudimentary oneline display. He is more accustomed of the large colorful touch screens of actual handle devices. But, the HP41C is also a handle that you tap on with your fingers, but not on its display, on its keyboard !! I put below the result of our collaboration so that you can now have the four temperature scale conversions on your machine. 001 LBL"TCONV" 002 SF 27 "A:F B:K C:C D:R" PROMPT 005 LBL A 1 "F" XEQ 10 009 LBL B 2 " K" XEQ 10 013 LBL C 3 "C" XEQ 10 017 LBL D 4 "R" XEQ 10 GTO A 022 LBL 00 CF 01 CF 02 CF 03 CF 04 RTN 028 LBL 01 FC?C 04 XEQ 04 459.67  RTN 034 LBL 02 FC?C 03 XEQ 03 273.15 + RTN 040 LBL 03 FC?C 01 XEQ 01 32  1.8 / RTN 048 LBL 04 FC?C 02 XEQ 02 1.8 * RTN 054 LBL 10 055 X<>Y FC?C 22 XEQ IND Y XEQ 00 SF IND Y STO IND Y 061 ASTO L CLA FIX 2 ARCL X FC? 02 "~ ." ARCL L PROMPT 069 END But I invite you to do like us and tap your own code on your favorite machine with your own digits. 

02112024, 07:30 AM
Post: #12




RE: HP Calculators with native CF temperature conversion
Thank you, Thomas Klemm, for your indepth reply. Either I had a program like the one you wrote up, or it could have been another model. The calculators I first bought years after the HP25 included the HP19C, HP55, HP67, HP95LX, HP100LX, HP200LX, HP75C, HP71B, HP41C and others. Also, and I hesitate to mention, the TI59 (gasp!). It might have been one of those. I know that doing this on an HP55 wasn’t necessary, but perhaps I just wanted to show off to myself that I could do it. I will have to scour the PPC Journal to see if I wrote it up, or stole the idea from someone else.


02112024, 08:34 AM
Post: #13




RE: HP Calculators with native CF temperature conversion
The HP 32E has temperature conversions and was introduced before 1980.
Pauli 

02112024, 10:03 AM
Post: #14




RE: HP Calculators with native CF temperature conversion
The HP 32S II also had native temperature conversion.


02112024, 03:31 PM
Post: #15




RE: HP Calculators with native CF temperature conversion
The rare HP31E also has keys for temperature conversion.
The powerful HP67 can also be programmed. But if you're organized enough, you can grab the dedicated program magnetic cards for these specific conversions. (And if you're really lucky, the magnetic reader might still be able to read it again  No need to retype programs, that would be so much easier!). Did anyone know the name of this specific magnetic cards pack ? 

02112024, 05:09 PM
Post: #16




RE: HP Calculators with native CF temperature conversion  
02132024, 02:29 PM
Post: #17




RE: HP Calculators with native CF temperature conversion
It seems that the HP32E would be another alternative to get instead of the HP55 with that temperature conversion and LED display. For now I downloaded the Panamatik HP32 simulation and it works just fine, although the blue lettering on the keys is not very clearly visible due to the angle of visualization being a bit too steep. But it works until I can find the real deal.
Too bad the HP34C does not have that temperature function, as I could have converted one of my surplus HP21s to it with the Panamatik keyboard overlay that I already have but so far have never gotten around to use. Some time ago already did convert a HP21 to a HP29C, and also brought back to life one HP25 and a HP27 with Bernhard's ACT. Thanks everyone for all the information. 

02132024, 03:09 PM
Post: #18




RE: HP Calculators with native CF temperature conversion
The mighty HP67 actually also had temperature conversion ...
Alas not preprogrammed or built in, but on the back label (together with some other conversions): Quote:FAHRENHEIT = 1.8 CELSIUS + 32 So, easy to remember and easy to program if you would need it ... ! Cheers, Thomas [35/45/55/65/67/97/80 21/25/29C 31E/32E/33EC/34C/38E 41CCVCX 71B 10C/11C/12C/15CCE/16C 32SSII/42S 28CS 48GX/49G/50G 35S 41X] 

02132024, 06:01 PM
Post: #19




RE: HP Calculators with native CF temperature conversion  
02152024, 10:55 AM
Post: #20




RE: HP Calculators with native CF temperature conversion  
« Next Oldest  Next Newest »

User(s) browsing this thread: 1 Guest(s)