HP-80 Unexplained Key Sequence?
06-21-2014, 07:37 PM
Post: #1
 Max Stone Junior Member Posts: 5 Joined: Jun 2014
HP-80 Unexplained Key Sequence?
Can anyone tell me why the HP-80 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
06-21-2014, 08:11 PM
Post: #2
 Massimo Gnerucci Senior Member Posts: 1,802 Joined: Dec 2013
RE: HP-80 Unexplained Key Sequence?
(06-21-2014 07:37 PM)Max Stone Wrote:  Can anyone tell me why the HP-80 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

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
06-21-2014, 08:15 PM
Post: #3
 Max Stone Junior Member Posts: 5 Joined: Jun 2014
RE: HP-80 Unexplained Key Sequence?
Thanks, interesting...one of those unexplained features of these early HP calculators.

Kind regards, MAX
06-21-2014, 08:26 PM (This post was last modified: 06-21-2014 10:00 PM by Martin Paech.)
Post: #4
 Martin Paech Junior Member Posts: 19 Joined: Dec 2013
RE: HP-80 Unexplained Key Sequence?
Unfortunately, with respect to the HP-80 I can't help, but this sequence (apparently) of integers might be of general interest (it's not in the OEIS).
06-21-2014, 08:35 PM (This post was last modified: 06-21-2014 08:42 PM by Martin Paech.)
Post: #5
 Martin Paech Junior Member Posts: 19 Joined: Dec 2013
RE: HP-80 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…
06-22-2014, 04:40 AM
Post: #6
 bshoring Member Posts: 259 Joined: Dec 2013
RE: HP-80 Unexplained Key Sequence?
Max, does this also change the display on yours to zero places? On my HP-80 iOS emulator it does.

Bob
06-22-2014, 05:36 PM
Post: #7
 rprosperi Senior Member Posts: 3,683 Joined: Dec 2013
RE: HP-80 Unexplained Key Sequence?
By coincidence, I just got a beautiful HP-80 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 HP-35 2.02 bug is well known, but are there analogous HP-80 bugs in history books?

--Bob Prosperi
06-22-2014, 05:47 PM
Post: #8
 HP67 Senior Member Posts: 610 Joined: Dec 2013
RE: HP-80 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
06-26-2014, 04:25 AM
Post: #9
 Thomas Klemm Senior Member Posts: 1,448 Joined: Dec 2013
RE: HP-80 Unexplained Key Sequence?
(06-22-2014 05:36 PM)rprosperi Wrote:  The HP-35 2.02 bug is well known, but are there analogous HP-80 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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