#ti92 — Public Fediverse posts

I just completed "Printing Department" - Day 4 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/4

Part 2 took more than 12 hours on my #Ti92 #GraphingCalculator, and it is already an optimized version. No clue how long the naive approach (part 1 in a loop) would have taken...

https://git.grois.info/aoc-2025/tree/day4

I just completed "Printing Department" - Day 4 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/4

Part 2 took more than 12 hours on my #Ti92 #GraphingCalculator, and it is already an optimized version. No clue how long the naive approach (part 1 in a loop) would have taken...

https://git.grois.info/aoc-2025/tree/day4

I just completed "Printing Department" - Day 4 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/4

Part 2 took more than 12 hours on my #Ti92 #GraphingCalculator, and it is already an optimized version. No clue how long the naive approach (part 1 in a loop) would have taken...

https://git.grois.info/aoc-2025/tree/day4

I just completed "Printing Department" - Day 4 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/4

Part 2 took more than 12 hours on my #Ti92 #GraphingCalculator, and it is already an optimized version. No clue how long the naive approach (part 1 in a loop) would have taken...

https://git.grois.info/aoc-2025/tree/day4

I just completed "Printing Department" - Day 4 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/4

Part 2 took more than 12 hours on my #Ti92 #GraphingCalculator, and it is already an optimized version. No clue how long the naive approach (part 1 in a loop) would have taken...

https://git.grois.info/aoc-2025/tree/day4

#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 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.)

#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.)

#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.)

#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.)

#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.)

#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.

#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.

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

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

#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 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.

#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

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

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

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.

#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.

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.

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.

I just completed "Gift Shop" - Day 2 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/2

On my #Ti92 #GraphingCalculator. Part2 took quite a while to finish. Not sure if that's normal or if there's a bug...

In any case, the result was correct, so I'm happy.

https://git.grois.info/aoc-2025/tree/day2

I just completed "Gift Shop" - Day 2 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/2

On my #Ti92 #GraphingCalculator. Part2 took quite a while to finish. Not sure if that's normal or if there's a bug...

In any case, the result was correct, so I'm happy.

https://git.grois.info/aoc-2025/tree/day2

I just completed "Gift Shop" - Day 2 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/2

On my #Ti92 #GraphingCalculator. Part2 took quite a while to finish. Not sure if that's normal or if there's a bug...

In any case, the result was correct, so I'm happy.

https://git.grois.info/aoc-2025/tree/day2

I just completed "Gift Shop" - Day 2 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/2

On my #Ti92 #GraphingCalculator. Part2 took quite a while to finish. Not sure if that's normal or if there's a bug...

In any case, the result was correct, so I'm happy.

https://git.grois.info/aoc-2025/tree/day2

I just completed "Gift Shop" - Day 2 - Advent of Code 2025 #AdventOfCode https://adventofcode.com/2025/day/2

On my #Ti92 #GraphingCalculator. Part2 took quite a while to finish. Not sure if that's normal or if there's a bug...

In any case, the result was correct, so I'm happy.

https://git.grois.info/aoc-2025/tree/day2

#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

#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

#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

#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

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

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

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

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

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

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

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

My #adventOfCode solutions this year will be in #LuaLang and will be ranked by the smallest machine they run on:

• Desktop
• Raspberry Pi 2
• #hp200lx
• #ti92 Plus

My #adventOfCode solutions this year will be in #LuaLang and will be ranked by the smallest machine they run on:

• Desktop
• Raspberry Pi 2
• #hp200lx
• #ti92 Plus

Putting Lua through its paces. Here's Advent of Code 2024, Day 13, running on all my favorite hardware that I had on hand, through the power of Lua.

Ryzen 5 9600X modern desktop - 1 ms.

HP 200LX, 8 MHz 186, 640 KB RAM available to Lua: 62 seconds.

TI-92+, 12 MHz 68000, 64 KB RAM available to Lua: 65 seconds.

"Write once, run anywhere".

#retrocomputing #lualang #ticalc #ti92 #hp200lx

Putting Lua through its paces. Here's Advent of Code 2024, Day 13, running on all my favorite hardware that I had on hand, through the power of Lua.

Ryzen 5 9600X modern desktop - 1 ms.

HP 200LX, 8 MHz 186, 640 KB RAM available to Lua: 62 seconds.

TI-92+, 12 MHz 68000, 64 KB RAM available to Lua: 65 seconds.

"Write once, run anywhere".

#retrocomputing #lualang #ticalc #ti92 #hp200lx

Okay, Lua 5.2.4 is much happier on the TI-92+ hardware. After loading the interpreter, there's about 64K free memory, which is enough to get up to some real trouble!
#ticalc #ti92 #retrocomputing