HP-15C CE woes: 1 bug, 2 limitations, 3 questions

[EdS2]

(08-08-2023 05:34 PM)Valentin Albillo Wrote:  The undocumented HP-16C mode's DEC bug.

For the record, mentioned here by Joe Horn and with detail here:

(08-07-2023 08:15 AM)Joe Horn Wrote:  

(08-07-2023 07:59 AM)ThomasF Wrote:  Is there any more info on this bug?

It only seems to happen in DEC mode. Example: repeatedly pressing the 1 key should make 1, then 11, then 111, and so on, appear. But instead, the following numbers SEEM to appear:
1
11
105
1111
11111
111111
1086535
11111111
110717895
1111111111
11111111111
111010447815
and so on, nonsensically but repeatably. When the wrong number appears, it's actually the correct value internally... it's only displayed incorrectly. It's displayed correctly in HEX, OCT, and BIN modes.

However, perhaps we should discuss this bug in its own thread so that large Fibonacci numbers can continue to be discussed in this thread.

Another set of examples from Voldemar here:

(08-07-2023 09:50 AM)Voldemar Wrote:  

(08-07-2023 08:15 AM)Joe Horn Wrote:  repeatedly pressing the 1 key

Not only [1] key
222 gives 216 on the screen;
33333 -> -32203;
44444 -> -21092;
55555 -> -09885;
7777 -> 6241;
999 -> 903
DEC is not usable

I wonder if by thinking hard one could come up with some mechanism which would cause the binary to decimal display conversion to produce these incorrect representations. This is a mini-challenge of its own.