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

[J-F Garnier]

To speak about something else than the 16c bug, that is after all not the main purpose of the CE:

(08-08-2023 05:34 PM)Valentin Albillo Wrote:  But now, with the CE/192 extended memory mode you have 3x the memory and thus up to 1,344 program steps. Even if using just 900 steps max (and still having about 66 data registers available) you might be tempted to create a big program and/or include many short ones in that much room, but the subsequent problem is that you'll have to carefully modify them to cater for duplicate labels. In short, having only 25 labels is quite a serious limitation now. And there's a possible additional problem with that much program memory in use, see the questions below.

Quote:But now, with the 192 registers provided by the CE/192 mode, there are practical cases where the limit of max 5 matrices at the same time is exasperatingly restrictive, e.g. you can't have, say, a 4-block partitioned matrix and easily use concise, fast block operations to work with it because of the 5-matrices limit, so you're having to jump through far too many hoops and annoyances to try and succeed.

It seems to me a bit paradoxal that more resources are seen as limitations.
My answer would be: take the CE/192 as an enhanced 15c, or to say it differently a 15c without the memory limitations of the original, but not as a new machine.

With 192 registers, you can, without changing the standard 19 storage registers allocation:
- use two 8x8 matrices (128 registers) and still have the 46 registers of the original 15C for programming,
- or solve a 8x8 system (64+8+8 registers), use the integrate/solve features (23 reg.), the complex mode (5 reg.) all together, and still have 66 registers for programming.
For me it's the key: you can use several (potentially all) 15c features at the same time without being limited by the memory.
This is much more interesting for me than attempting to write long programs, which is not practical anyway (see my last comments below).

Quote:Anyway, I find it sad that HP didn't consider including the instructions BGTO/BGSB (backwards GTO/GSB,) identical to GTO/GSB except that they would search backwards for the label instead of forwards (so code like the following would've been possible,) alleviating or completely voiding the need for additional labels, with minimum microcoding and ROM space needed to implement both:

We can try to revisit the past but HP never did such a thing, indeed.
Machines of that time had limited memory, and such optimization was just not needed.
When the 41C appeared with its potentially larger memory, HP chose to implement compiled GTO, which was more efficient and simpler to the user.

For me, the main limitation of the 15c is the fact that program steps are still recorded as keycodes.
This seems to me absolutely archaic in 2023. I really would welcome a 15c with clear instructions à la 41C: LbL, STO, RCL, ...
It would not break any compatibility and would give a tremendous comfort for programming.
The 41C series introduced this innovative feature in 1979, unfortunately the 1981 Voyager series went back to keycodes.
It was a big step backward at the time, and I remember that I initially didn't like this series for this very reason.

J-F