HP80 Unexplained Key Sequence?

06212014, 07:37 PM
Post: #1




HP80 Unexplained Key Sequence?
Can anyone tell me why the HP80 gives this unusual, unexplained sequence when you keep pressing Shift then the Decimal Point, giving you the following sequence (from an empty stack):
0. 1. 2. 3. 5. 11. 26. 66. 227. 1064. 6257. 62979. 1251797. 41590664. 4048283972. Kind regards, MAX 

06212014, 08:11 PM
Post: #2




RE: HP80 Unexplained Key Sequence?
(06212014 07:37 PM)Max Stone Wrote: Can anyone tell me why the HP80 gives this unusual, unexplained sequence when you keep pressing Shift then the Decimal Point, giving you the following sequence (from an empty stack): We've already been here... :) Greetings, Massimo +×÷ ↔ left is right and right is wrong 

06212014, 08:15 PM
Post: #3




RE: HP80 Unexplained Key Sequence?
Thanks, interesting...one of those unexplained features of these early HP calculators.
Kind regards, MAX 

06212014, 08:26 PM
(This post was last modified: 06212014 10:00 PM by Martin Paech.)
Post: #4




RE: HP80 Unexplained Key Sequence?
Unfortunately, with respect to the HP80 I can't help, but this sequence (apparently) of integers might be of general interest (it's not in the OEIS).


06212014, 08:35 PM
(This post was last modified: 06212014 08:42 PM by Martin Paech.)
Post: #5




RE: HP80 Unexplained Key Sequence?
Thank you for the link, Massimo! Gerson W. Barbosa has also checked the OEIS in 2012: How about to publish this curious sequence?
Martin Edit: Till now HP is only mentioned in two sequences… 

06222014, 04:40 AM
Post: #6




RE: HP80 Unexplained Key Sequence?
Max, does this also change the display on yours to zero places? On my HP80 iOS emulator it does.
Bob 

06222014, 05:36 PM
Post: #7




RE: HP80 Unexplained Key Sequence?
By coincidence, I just got a beautiful HP80 from TAS 2 days ago, and while playing with it, I entered repeated 8's to verify the LED segments, and discovered it does a similar (by that I mean unexpected) thing.
Initially of course, it fills the display left to right, but once filled, the exponent field grows by 1 for each addional press of 8, or indeed any numeric entry key. As noted above, just another unexpected result (as opposed to bug I suppose) which was 'corrected' in later models. Of interest, the s/n begins 1247... meaning one of the earlier units produced, since Introduction was 1973. The HP35 2.02 bug is well known, but are there analogous HP80 bugs in history books? Bob Prosperi 

06222014, 05:47 PM
Post: #8




RE: HP80 Unexplained Key Sequence?
Wow, what a beautiful calculator. I had to look that one up. I had not heard about it.
It ain't OVER 'till it's 2 PICK 

06262014, 04:25 AM
Post: #9




RE: HP80 Unexplained Key Sequence?
(06222014 05:36 PM)rprosperi Wrote: The HP35 2.02 bug is well known, but are there analogous HP80 bugs in history books? There's a display bug (search for the title: "End Note  Bugs?") and another one concerning \(\Sigma\)+ described in my Message #10 posted on 13 Feb 2012. Cheers Thomas 

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