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

[brouhaha]

Quote::
1
11
105
1111
11111
111111
1086535
11111111
110717895
1111111111
11111111111
111010447815
and so on, nonsensically but repeatably.

The incorrect entries are all failed BCD adjustment in the conversion between the internal binary representation and decimal. Note that every error is by an amount 6 x 16^n for a small non-negative integer n.

It's possible that there could be related error cases where the delta is the sum of 6x16^n terms for multiple values of.n.

(08-07-2023 09:50 AM)Voldemar Wrote:  Not only [1] key
222 gives 216 on the screen;
33333 -> -32203;
44444 -> -21092;
55555 -> -09885;
7777 -> 6241;
999 -> 903

These are a mix. Some are the 6x16^n problem, but I suspect the others, wheee the displayed value is negative, are actually "correct", as it appears that the calculator was in the default 16-bit two's complement mode.