HP41C T register duplication disabling

02192020, 06:16 PM
Post: #1




HP41C T register duplication disabling
Good evening, I am sorry if this question was already asked (I found nothing) or if it is in the wrong section (I will try to change its position in this case).
My question is if it is possible to disable T register duplication on HP41C because I don't need this feature and I find it a bit annoying. In the user manual I couldn't find any useful information. I am sorry for my english. Ranieri 

02192020, 08:34 PM
Post: #2




RE: HP41C T register duplication disabling
(02192020 06:16 PM)Ranieri Wrote: Good evening, I am sorry if this question was already asked (I found nothing) or if it is in the wrong section (I will try to change its position in this case). Short answer: No. Greetings, Massimo +×÷ ↔ left is right and right is wrong 

02192020, 08:40 PM
Post: #3




RE: HP41C T register duplication disabling
(02192020 08:34 PM)Massimo Gnerucci Wrote:(02192020 06:16 PM)Ranieri Wrote: Good evening, I am sorry if this question was already asked (I found nothing) or if it is in the wrong section (I will try to change its position in this case). Grazie 

02202020, 04:53 PM
Post: #4




RE: HP41C T register duplication disabling
It's an interesting question. Suppose it was possible to disable T register duplication. What would you put in the T register instead?
In other words, suppose you key in 1 ENTER 2 ENTER 3 ENTER 4 + What would you want the stack to contain? T: ? Z: 1 Y: 2 X: 7 Dave 

02202020, 05:06 PM
Post: #5




RE: HP41C T register duplication disabling
(02192020 06:16 PM)Ranieri Wrote: Good evening, I am sorry if this question was already asked (I found nothing) or if it is in the wrong section (I will try to change its position in this case). It's a fundamental feature of all the HP RPN calculators with a fixed size stack. There are other HP calculators ("RPL" calculators such as HP 28/48/49/50 series and HP Prime in RPN mode) that have a stack that grows and shrinks with no duplication of the "top" element. — Ian Abbott 

02202020, 06:28 PM
Post: #6




RE: HP41C T register duplication disabling
(02202020 04:53 PM)David Hayden Wrote: It's an interesting question. Suppose it was possible to disable T register duplication. What would you put in the T register instead? Thank you for your reply, probably I would expect it to contain 0 just like the other registers. Ranieri 

02202020, 06:53 PM
Post: #7




RE: HP41C T register duplication disabling
(02202020 06:28 PM)Ranieri Wrote:(02202020 04:53 PM)David Hayden Wrote: It's an interesting question. Suppose it was possible to disable T register duplication. What would you put in the T register instead? That's how some other old RPN machines work. For instance on the Novus Mathematician, when you clear (drop) the xelement, the stack goes down and the top element is cleared. Almost like the RPL (although the Novus stack was *3* elements high). Novus as a RPL precursor? JF 

02202020, 07:01 PM
Post: #8




RE: HP41C T register duplication disabling  
02202020, 09:03 PM
Post: #9




RE: HP41C T register duplication disabling
I'm not sure it makes any difference. Uninitialized registers or variables, whether they contain 0 or any random value, will lead to problems either way. I have however seen instruction sequences that take advantage of the fact that T gets duplicated as the stack drops.
http://WilsonMinesCo.com (Lots of HP41 links at the bottom of the links page, http://wilsonminesco.com/links.html ) 

02212020, 08:03 AM
(This post was last modified: 02212020 08:04 AM by AndiGer.)
Post: #10




RE: HP41C T register duplication disabling
E.g. there is a simple but very useful memory test program for HP97 and HP67 that makes use of the T register being duplicated:
https://www.hpmuseum.org/cgisys/cgiwrap...ead=129900 OK, were are talking about HP41 in this thread... 

02212020, 01:49 PM
Post: #11




RE: HP41C T register duplication disabling
(02202020 09:03 PM)Garth Wilson Wrote: I have however seen instruction sequences that take advantage of the fact that T gets duplicated as the stack drops. One of them is the evaluation of polynomomial expressions using the Horner method. Quoting from the HP15C manual, pages 79 and 80:  Polynomial Expressions and Horner's Method Some expressions, such as polynomials, use the same variable several times for their solution. For example, the expression f(x) = Ax⁴ + Bx³ + Cx² + Dx + E uses the variable x four different times. A program to solve such an equation could repeatedly recall a stored copy of x from a storage register. A shorter programming method, however, would be to use a stack which has been filled with the constant (refer to Loading the Stack with a Constant, page 41). Horner's Method is a useful means of rearranging polynomial expressions to cut calculation steps and calculation time. It is especially expedient in SOLVE and ∫x,y, two rather longrunning functions that use subroutines. This method involves rewriting a polynomial expression in a nested fashion to eliminate exponents greater than 1: Ax⁴ + Bx³ + Cx² + Dx + E (Ax³ + Bx² + Cx + D)x + E ((Ax² + Bx + C)x + D)x + E (((Ax + B)x + C)x + D)x + E Example: Write a program for 5x⁴ + 2x³ as (((5x + 2)x)x)x, then evaluate for x = 7 Keystrokes Display g P/R 000 Assumes position in memory is line 000. If it is not, clear program memory. f LBL B 00142,21,12 5 002 5 * 003 20 5x 2 004 2 + 005 40 5x + 2. * 006 20 (5x + 2)x. * 007 20 (5x + 2)x². * 008 20 (5x + 2)x³. g RTN 009 43 32 g PR Return to Run mode. Prior result remains in display 7 ENTER ENTER ENTER 7.0000 Loads the stack (X, Y, Z, and T registers) with 7. f B 12,691.000  

02212020, 02:28 PM
Post: #12




RE: HP41C T register duplication disabling
Here's an interesting challenge  one I'm not sure I have a good solution for yet: what's the fewest number of steps needed to guarantee that the value in T is different from the value in Z, while preserving the contents of X, Y, Z, and L?


02212020, 02:33 PM
Post: #13




RE: HP41C T register duplication disabling
(02212020 02:28 PM)Dave Britten Wrote: Here's an interesting challenge  one I'm not sure I have a good solution for yet: what's the fewest number of steps needed to guarantee that the value in T is different from the value in Z, while preserving the contents of X, Y, Z, and L?STO T // copy X in T and satisfy your request. 

02212020, 02:34 PM
Post: #14




RE: HP41C T register duplication disabling
(02212020 02:33 PM)Sylvain Cote Wrote:(02212020 02:28 PM)Dave Britten Wrote: Here's an interesting challenge  one I'm not sure I have a good solution for yet: what's the fewest number of steps needed to guarantee that the value in T is different from the value in Z, while preserving the contents of X, Y, Z, and L?STO T // copy X in T and satisfy your request. Not if X=Z, though. Then you still have T=Z. 

02212020, 03:27 PM
Post: #15




RE: HP41C T register duplication disabling
(02212020 02:34 PM)Dave Britten Wrote:He! Ho! you are cheating that constraint was not in the original request. LOL(02212020 02:33 PM)Sylvain Cote Wrote:Not if X=Z, though. Then you still have T=Z.(02212020 02:28 PM)Dave Britten Wrote: Here's an interesting challenge  one I'm not sure I have a good solution for yet: what's the fewest number of steps needed to guarantee that the value in T is different from the value in Z, while preserving the contents of X, Y, Z, and L?STO T // copy X in T and satisfy your request. 

02212020, 03:44 PM
Post: #16




RE: HP41C T register duplication disabling
(02212020 03:27 PM)Sylvain Cote Wrote:(02212020 02:34 PM)Dave Britten Wrote: Not if X=Z, though. Then you still have T=Z.He! Ho! you are cheating that constraint was not in the original request. LOL That's an edge case, not a constraint. Simply guarantee that T does not equal Z, and leave X, Y, Z, and L as you found them. There are lots of edge cases for this  zeroes, alpha data, etc.  that make this a good deal trickier than it seems at first. 

02252020, 09:01 AM
(This post was last modified: 02252020 09:03 AM by Didier Lachieze.)
Post: #17




RE: HP41C T register duplication disabling
(02212020 02:28 PM)Dave Britten Wrote: Here's an interesting challenge  one I'm not sure I have a good solution for yet: what's the fewest number of steps needed to guarantee that the value in T is different from the value in Z, while preserving the contents of X, Y, Z, and L? Here is a program for the HP 41 /42S that should meet this challenge. With 15 steps it’s not very short and I’m looking to the RPN experts on this forum for better solutions. Code: 00 { 28Byte Prgm } 

02252020, 09:47 AM
(This post was last modified: 02252020 09:52 AM by Werner.)
Post: #18




RE: HP41C T register duplication disabling
I wonder what the use is, but here goes
works even when Z and/or T contains string data or complex numbers. 1. keeping T intact if it was different from Z to start with Code: >LBL "T#Z" 2. destroying T Code: >LBL "T#Z" Cheers, Werner 

02252020, 10:10 AM
Post: #19




RE: HP41C T register duplication disabling
These functions are included in Angel's WarpCore module for the 41, written in MCode. You can for example exchange T and Z, or compare T to Z, in a single instruction.
http://WilsonMinesCo.com (Lots of HP41 links at the bottom of the links page, http://wilsonminesco.com/links.html ) 

02252020, 03:26 PM
Post: #20




RE: HP41C T register duplication disabling  
« Next Oldest  Next Newest »

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