The 45 with a 15C twist


Hello all,

I've read in John A. Ball's bible, "Algorithms for RPN Calculators" that some early 45s had Recall Arithmetic exactly like the 42S and 15C. Does anyone have the serial number run of these 45s?


Edited: 4 Apr 2012, 5:24 p.m.



HP has not been consistent in implementing RCL arithmetic in all of its calculators. This feature appears in some models but not others.



Yes, as per the book, it mentions how earlier models have the feature but later versions do not.


It's fun to use the museum's calculator compare feature 2 c this.


I've been using that quite a bit lately. Very handy. Quite informative.


All HP-45's had Recall arithmetic like the 42S and 15C. The difference between early and later models was in Store arithmetic. In early models, STO-n would subtract the value in register n from the value in stack X, and store the result in register n. Similarly, STO/n would divide the value in register n into the value in stack X, storing the result in register n. In later models, STO-n would subtract the value in stack X from the value in register n, and STO/n would divide the value in stack X into the value in register n. As for when the change occurred, I have a version 1 (with the raised metal bar at the top of the keyboard instead of the silver trim), S/N 1301A04xxx which has the former behavior and another, S/N 1350A89xxx which has the latter. I know that there are serial numbers which begin 1349 that also have the later behavior. I have no knowledge of other S/N series numbers and do not know when the change-over occurred.

Edited: 6 Apr 2012, 11:38 p.m.

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP-41 New versions of your favorite modules - with an AOS twist :-) Ángel Martin 13 4,228 06-21-2013, 01:29 PM
Last Post: Diego Diaz
  Repair HP 45 Nanoman 3 772 04-12-2013, 05:40 PM
Last Post: BobVA
  Recharging original batteries in HP 45, 65 and 25 Michae Altmann 1 706 03-05-2013, 12:21 AM
Last Post: DavidShenk
  OT: Google evaluates mathematic expressions (with a twist) DavidShenk 4 1,099 02-13-2013, 09:05 AM
Last Post: Juan J
  HP 45 versions james summers 18 2,817 04-14-2012, 02:36 AM
Last Post: Eric Smith
  My new kid has arrived! It's a 45! Matt Agajanian 5 1,073 04-05-2012, 05:46 AM
Last Post: Harald
  21, 45, 32E--which should be next? Matt Agajanian 14 2,104 03-25-2012, 02:48 AM
Last Post: Thomas Radtke
  If the 21 came after the 45...? Matt Agajanian 5 1,084 03-24-2012, 05:45 PM
Last Post: Matt Agajanian
  Strange HP-45 Michel Beaulieu 4 959 03-01-2012, 04:34 AM
Last Post: McAllan
  Original 15C Keyboard Test Works With 15C LE!!! DigiGal 5 1,326 09-26-2011, 07:33 PM
Last Post: M. Joury

Forum Jump: