I just tested with Batocera - https://updates.batocera.org/x86_64/stable/last/batocera-x86_64-x86_64-39-20240304.img.gz
(website - https://batocera.org/download) Desktop PC, Laptop, NUC and Intel-based Apple Computers
> unzip to .img file, with Win32mgr write to a USB stick (Sandisk 64 gb and bootup on the PC (Beelink Ser5), then a bluescreen appears, press key and boot Batocera.
> press F1 (for the file system)
> copy (from another USB stick or disk the .rpk files into SHARE/roms/ti99 (search on ftp.whtech.com in the batoceraretrobat)
> copy in SHARE/bios the ti99_4a.zip and the ti99_speech.zip
> Press spacebar > Game Settings > Update Gamelists (then Esc), now the TI99 is listed in the menu
> Press spacebar > Game Settings > Per System configuration > TI99 > Emulator > MAME
(Note: Libretro/MAME, it seems to have issues with sound and keymapping, like ENTER)
(I did not had sound at first):
> press spacebar -> System Settings -> Audio ouput -> select the right sound option
Now > TI-99 - > select your TI game -> press Esc (this takes a while on my system, somehow Batocera is a bit slower than Retrobat, maybe because it runs of the USB)
> Some hotkeys: ESC to get back to Batocera. (or CTRL-ESC in Libretro/MAME)
> or SELECT + START on a controller
> TAB (to configure MAME itself)
> Using Controllers
> Wired might work the best, Wireless I am using issues with PS4 controllers and Bluetooth (discovered okay, mapped okay, but after standby does not associate anymore and cannot delete and rediscover)
> XINPUT controllers might work better as MAME prefers it. (that's why I use Windows with Retrobat and DS4Windows and Hide to use wireless PS4 controllers in XINPUT mode)
> Mapping TI-keys.
> Press spacebar > Game Settings > Per System configuration > TI99 > PAD2Key file.
> e.g. map keys like 1, 2, 3 to to Y, A, B buttons on a PS4 controller
> multi-combination keys e.g. FCTN-QUIT map it to (right) ALT and = (when you see the keyboard at the bottom of the screen you see the option how to configure combination keys)
> or configure FCTN-BACK and FCTN-REDO (I map it to the Right Analog Stick).
> and configure SELECT to 5 (e.g. for Mario Bros to insert a coin)
Then most TI games you can play without touching the keyboard.
Hope this helps for your Batocera setup.