Complex TI-57 Programs

[Matt Agajanian]

Hi all.

Now that there's TI-57 for iOS, RCL-57, the opportunities of writing programs are possible. Even with its short program memory, limited parentheses/pending operations limits, pair of subroutine levels, and registers in which one register is used for scientific functions, I’m sure the 57 has some robust potential. So, what programs have you written that pushed the 57 to its potential?

[pauln]

As I reported earlier, for me it was:

• Lunar Lander
• Biorhythms
  

The TI-57 being mostly an educational tool, it doesn't seem to have many complex programs. But I believe it has potential. In fact it is not too far from the HP-25:

Tie: both calculators have fully merged steps

TI-57 advantage

• subroutines
• 1 additional step (50 vs 49)
  

HP-25 advantage

• can go to an arbitrary step (GTO nn). In a TI-57 you have to declare labels and that takes 1 additional step per label
• both have 8 registers but TI-57 uses Reg 7 for comparisons
• RPN vs AOS. But note that an efficient TI-57 program would rarely/never use parentheses. Instead it will use arithmetic on registers (SUM n, Prd n, etc.)
  

[Steve Simpkin]

(08-12-2022 11:08 PM)pauln Wrote:  As I reported earlier, for me it was:

• Lunar Lander
• Biorhythms
  

The TI-57 being mostly an educational tool, it doesn't seem to have many complex programs. But I believe it has potential. In fact it is not too far from the HP-25:

Tie: both calculators have fully merged steps

TI-57 advantage

• subroutines
• 1 additional step (50 vs 49)
  

HP-25 advantage

• can go to an arbitrary step (GTO nn). In a TI-57 you have to declare labels and that takes 1 additional step per label
• both have 8 registers but TI-57 uses Reg 7 for comparisons
• RPN vs AOS. But note that an efficient TI-57 would rarely/never use parenthesis. Instead it will use arithmetic on registers (SUM n, Prd n, etc.)
  

After briefly studying the TI-57 manual I would also add the following advantages
TI-57 advantage

• Labels (see next)
• Ability to add/delete instructions. With its use of labels, this allows you to edit a program without resorting to overwriting instructions with NOPs or overwriting large sections of your program because you cannot insert instructions on the HP-25. Even if you could, the lack of labels would likely require changing GTO instruction lines. This comes from a 10 year user of the HP-25 and is not a criticism (the HP-25 delivered far more than it started out with on the drawing board), but a long desired feature.
• Can perform 2 data point Statistics.
• Can calculate the Variance in Statistics.
• Has "normal" or "standard" display mode that displays only the number of digits after the decimal point that are needed (via FIX 9 or INV FIX).
• Can calculate Xth root.
• Has an EXC function which can exchange the number in memory N with the displayed number.
• Cost much less.
  

HP-25 advantage

• All available functions and instructions are printed on the keyboard (except for register math). There are no hidden or potential obscure operations related to the TI-57's use of the INV key.
• Related to the above, register math key sequences are more obvious (STO - 1 instead of INV SUM 1).
• Two more conditional tests.
• Has Engineering display mode.
• Has forced Scientific display mode.
• Has a % function.
  

One additional undocumented advantage that the TI-57 has over the HP-25 model (not the HP-25C) is that you can turn the TI-57 display off which then draws so little power from the batteries that it is almost like having a constant memory function.
https://www.rskey.org/gene/calcgene/57c.htm

[Matt Agajanian]

Not sure if I mistakenly thought the transcendental functions used a register in the 57. So, if I’m mistaken, aside from the t register using R7, what other operations does the 57 use register 7 for?

[pauln]

For the statistic functions: register 7 holds the number of data points. For statistic functions, other user registers are used, for sum, sum of squares, etc.

No user register seems to be used for transcendental functions. I just checked with RCL-57 by going to the Register View.

[Steve Simpkin]

(08-13-2022 12:21 AM)pauln Wrote:  For the statistic functions: register 7 holds the number of data points. For statistic functions, other user registers are used, for sum, sum of squares, etc.

No user register seems to be used for transcendental functions. I just checked with RCL-57 by going to the Register View.

Here is the complete alternate use of memory locations from the TI-57 manual.
   

[pauln]

(08-13-2022 12:00 AM)Steve Simpkin Wrote:  [...] After briefly studying the TI-57 manual I would also add the following advantages [...]

Great summary. And it's true that some TI-57 features are kind of hidden: it took me a long time to find out that "INV C.t" clears out user registers.

And, as you point out later, one problem with the TI-57 is that registers 5 and 6 may be overridden "silently" when evaluating complex arithmetic expressions.

[Gene]

** Lots ** of the TI-57 data registers are dual purpose. Always have to be on guard to lose them if you are not careful.

Comparatively, the SR-56 beats the TI-57 in most regards.

Gene

[Thomas Klemm]

(08-12-2022 07:29 PM)Matt Agajanian Wrote:  So, what programs have you written that pushed the 57 to its potential?

Maybe this doesn't fit exactly: Binary-to-Decimal conversion
But since we're already comparing the TI-57 to the HP-25, this could be an interesting example.

Not sure if I was able to rewrite the N-Queens program for the TI-57.
It uses only storage arithmetic, so this could be translated verbatim.
But then we still need some additional steps for the labels.

[pauln]

There are also a couple of remarkable programs to compute the first 48 digits of e and all digits of 52! in a different thread:

https://www.hpmuseum.org/forum/thread-18...#pid163222

They use a 6-register "rotating stack with wrap-around" technique. This may be one case where the TI-57 has the advantage over the HP-25 which lacks "Exc n" (Exchange between the display and register n).