I used to code on my TI85 calc back in the late 1990s.

Thankfully ticalc.org has the games I uploaded.

But sadly due to an magnetic gremlins, I've lost the newest version of the source code and I only have a early version and a damaged later version. For one of my games I can piece together 90% of the code, for another not so much.

Annoyingly, I noticed I placed a dummy byte or two after some functions to thwart decompiling? Seems to be always after a ret op code.
Is there a good disassembler to tackle this problem?

I vaguely remember there being a ti-85 emulator. In fact I found some posts I wrote in the late 90s about it.
By now surely there are great emulators?

I still have my original ti-85, and have bought another. Also discovered a ti84 plus with its Flash ram disk. Bought it at a thrift store, amazing device.


Thanks for any help.

Tilem is the only emulator I know of that can target the 85, but should work for you.

For reverse-engineering, Ghidra supports Z80 and since it follows the control flow graph probably won't be confused by junk bytes that never actually get executed. I've used it for some calculator reverse-engineering in the past and found it worked pretty well (although it has a pretty steep learning curve).

Wabbitemu can also target the 85.

Today, I fetched some disassemblers and the disassembler from the Usgard author got close.

But I thought, why wouldn't I make multiple backups? Disks weren't that expensive. I have a bunch of disks from last century and my labeling was very inaccurate or blank. So disk after disk, I checked and labeled with pencil.
Finally, I found it! Another TI asm back up.

Now with the complete asm code, I see I have several checksums and other modification thwarting that would have made things difficult. I plan to open source the code but I will probably remove that annoying stuff.

The game has a level compiler that takes text files and compiles levels. Unfortunately I cannot find that C++ code, but hopefully I can reverse engineer that.

Update:
After 25 years, I've updated two of my TI-85 graphics calculator games: **Scrolls** and **Caves**. These retro games, written in Z80 assembly language, showcase the impressive performance of the TI-85 despite its hardware constraints.

GitHub repo (with source code): https://github.com/VroomDev/ti85
Bug fixes, more levels, and improvements included!

- **Scrolls**: A top-down dungeon crawler.
- **Caves**: A side-scroller exploring cave systems, dodging obstacles, and finding treasures.