Lmst

RE: https://hachyderm.io/@itworldcup/115949253823078683

Es musste sein.
#Rust für komplizierte Sachen. Wenn man mit Speicher jongliert und Sicherheit will. Aber es ist auch einfach ein tolles Gefühl, so nah am System zu sein wie in #C.
Und noch eine Sache, die für mich relevant ist: #LLVM unterstützt nur Prozessoren, deren Wortbreite eine Zweierpotenz ist. Ich schreibe gerne Programme für den #eZ80, der mit 24-bit-Wörtern einfach von modernen Sprachen nicht unterstützt wird.
Vielleicht kann man hier ja dafür werben.
#ticalc #swift

#adventOfCode day 12 in #LuaLang

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/12.lua

PC - 2ms
Raspberry Pi 2: 76ms
#ti92 Plus: Crashed

I wasn't expecting that to work!

And as usual, AoC is a good source of stressing cases to expose crashes/bugs in the #ticalc Lua port :p

Merry Christmas!
This is the first Advent of Code I've ever completed!

#adventOfCode day 10 in #LuaLang and #Mathematica

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/10.lua

PC - 487 ms
Raspberry Pi 4: a few seconds
#ti92 Plus: N/A

Ok, finally all caught up and looking forward to some sleep and Day 12!

After a night and day in math land confusing myself with row echelon matrices and intersecting N-spaces, I remembered that I have a Raspberry Pi that for some reason has free preinstalled Mathematica.

So my Lua program code-gens a Mathematica program, which then runs on the Pi to solve Part B!

This generated code is checked in if you want to look at it - it's several thousand lines of simultaneous equations being solved with constraints applied: https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/10.m

Given all that, it's pleasantly fast. Mathematica over VNC on wifi is pretty laggy but the actual execution couldn't have taken more than a second or two!

(Yes, I did attempt to solve the equations on the TI-92+ #ticalc, as it has a very capable computer algebra system, but I couldn't figure out how to apply all the necessary constraints -- maybe later.)

A Mathematica notebook running on Linux on a Raspberry Pi. Several lines of simultaneous equation solutions, denoting numbers of button presses, can be seen. A running total is also interspersed with these lines, the last line being the Part B solution.

#adventOfCode day 7 in #LuaLang

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/07.lua

PC - 1.5 ms
Raspberry Pi 2: 41 ms
#ti92 Plus: >18 min

After a couple of days where the TI-92+ has been disagreeable, it was refreshing to get a puzzle where the Lua solution Just Works without memory exhaustion. Though, speedy it ain't. And when I got my camera out to photograph the real calc, I found it had crashed, so you get a boring emulator screenshot of it working instead.... ;)

I'm a little confused why it's this slow on the #ticalc: something about it seems difficult compared to the other working examples. I think it's because my approach generates lots of garbage so Lua's gc is working hard.

TI-92+ emulator displaying Part A, B: 1633 34339203133559

For anyone interested in the port of #LuaLang I'm using for #AdventOfCode on the #Ti92 Plus graphing calculator, I've uploaded the patched Lua sources and prebuilt binaries for TI-89 and TI-92+ to https://gitlab.cs.washington.edu/fidelp/lua92
Please let me know if you try it out!

#ticalc #retrocomputing

$TI-92+ emulator running the Lua program: while true do if math.random() > 0.5 then io.write("/") else io.write("\\") end end which is the Lua equivalent of the famous "10 PRINT CHR..." C64 maze generator oneliner.$

#adventOfCode day 6 in #LuaLang

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/06.lua

PC - 5.1 ms
Raspberry Pi 2: 147 ms
#ti92 Plus: out of memory

I'm steadily accumulating a backlog that I need to rewrite into C for the #ticalc. I'm really jonesing to switch back to the DOS-based HP 200LX palmtop... 640K RAM feels mighty spacious in comparison to the calculator. Maybe in my copious spare time I need to track down the memory corruption problem that's stopping the 16-bit MS-DOS Lua from working.

#adventOfCode day 5 in #LuaLang

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/05.lua

PC - 1.7 ms
Raspberry Pi 2: 49 ms
#ti92 Plus: out of memory

The #ticalc doesn't make it through input parsing before exhausting memory. It will be necessary to rewrite in C again.

My port of #LuaLang to TI-92+ had a bug where math.huge was accidentally NaN instead of +∞. This is now fixed, so we can infinitely loop the fun way.

I like that the screen's slow update speed is clearly visible in the photo....

#ti92 #ticalc #retrocomputing

A TI-92+ looping to display the numbers between 1 and math.huge. So far, the numbers 1-111 are visible. The numbers 109, 110 and 111 are more and more obscure, with 111 barely legible, because this is a slow LED where it takes a moment for pixels to fade in after being set.

I just completed "Lobby" - Day 3 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/3

Again on a #Ti92 #TiCalc. Part 2 took over 30 minutes to run...
https://git.grois.info/aoc-2025/tree/day3

#adventOfCode day 4 rewritten in C

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/04.c

This is a very simpleminded solution with no algorithmic fanciness: it's performing lots of repeated work in Part B.

PC - 1 ms
Raspberry Pi 2: 23 ms
#ti92 Plus: 10 seconds

It was stunning to see a result returned in just 10 seconds on the #ticalc, rather than minutes for previous days. The performance difference between an interpreter and an optimizing compiler is stark! Also, the TI-92 doesn't have a floating-point coprocessor, which makes Lua in particular struggle to run at speed.

TI-92+ graphing calculator displaying:
Part A: 1451
Part B: 8701

The input for Day 3 of this year's #AdventOfCode is so long again, that I'm afraid that I will have to split it in order to allow my #Ti92 #TiCalc to process it...

At least part 1 seems to be simple enough to finish in a reasonable time on that ancient hardware.

@soulsource That's so cool, I didn't expect to find someone else solving the puzzles on a #ticalc! Are you using the original TI-92 or the Plus? What kind of run times are you getting? I have been using Lua on mine and all of my solutions are in the range 2-20 minutes, which seems incredibly slow.

#adventOfCode day 3 in #LuaLang, update: Execution time on my real #ti92 was 17m12s.

The TI-92+ appears to run Lua programs at 1/10,000 the speed of my Raspberry Pi 2B: that is, take the RPi execution time, shift to the next SI size category (like milliseconds to seconds) then multiply by ten, and you'll be in the ballpark.

Meanwhile, the Raspberry Pi is about 1/50 the speed of my desktop.

#ticalc #retrocomputing

Real TI-92+ displaying the same puzzle answers as the previous pic in the thread.

#adventOfCode day 3 in #LuaLang

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/03.lua

PC - 5.4 ms
Raspberry Pi 2: 156 ms
#ti92 Plus: ??? minutes (still running)

The program runs successfully in TiEmu with the emulation speed multiplier unlocked. It has yet to be seen how long it'll take on the real calc...

#ticalc #retrocomputing

TI-92 emulator displaying
Part A, B: 17193 171297349921310

The TI-34 is a fairly basic scientific #calculator. I’m a big fan because it’s easy to use and not overwhelming.

I was reading the manual and discovered it has two functions:

ipart(x)
fpart(x)

These return the integer and fraction parts of x.

ipart(2.34)=2
fpart(2.34)=.34

Great! So, uh.. What are these typically used for? Why include them on such a *basic* calculator? #calculators #ticalc #ti34 #matheducation #mathchat

On real hardware the Day 2 puzzle takes about 4 minutes to run!
#ticalc #ti92 #retrocomputing

Real TI-92+ displaying:
Part A, B: 19219508902 27180728081

Adapted #adventOfCode 2025 day 2 in #LuaLang to use a much more efficient algorithm to fit on #ti92 Plus.

https://gitlab.cs.washington.edu/fidelp/advent-of-code-2025/-/blob/main/02fast.lua

Desktop: 1.1 ms
Raspberry Pi 2B: 20 ms

This also found a bug in my port of Lua: math.huge was the wrong value, so a particular loop was never running.

#ticalc #ti92

TI-92+ emulator displaying Part A, B: ... answers to an Advent of Code puzzle

Because the post upthread has poor video quality, here's a higher res photo of the 2025 day 1 result on TI-92+.
#ticalc #ti92 #adventOfCode #LuaLang #retrocomputing

Adapted #adventOfCode 2025 day 1 in #LuaLang to use less memory to fit on #ti92 Plus. Execution time: 2m 42s.

The TI-92+ has a 12 MHz 68000 and 188 KB RAM that is also used as the calculator's main ramdisk, meaning, the Lua interpreter, script, puzzle input, and all datastructures must fit in that size. The calculator runs on 4 AA batteries with a battery life of "well beyond a school year".

#retrocomputing #ticalc