Only fMSX core is included and working at Retroarch (1.7.5) of PS VITA.
For some old MSX games such as Athletic land, Antarctic adventure, H.E.R.O, etc, numeric “1” ,“2”, “3” or “4” should be pushed to start the game instead of SPACE BAR or Joystick “A” button.
Even though I entered into “input” menu and try to remap keys to “1” ,“2”, “3” or “4” with PS VITA buttons such as select key, start key, L1 key, R1 key, etc, I cannot find any method to do that.
As you know well, touch function doesn’t well at retroarch of PSVITA and also it is impossible to connect actual keyboard to PS VITA to play such a game (Athletic land, Antarctic adventure).
So, I think the only best way to push numeric keys to start the games is to change Remap descriptors for “Joystick + Emulated keyboard” or “Emulated keyboard” in order to add numeric keys (“1”~“4”) in emulated keyboard settings.
Currently, very limited characters such as “F1”, “F2”, “F3”, “F4”, “F5”, “CTRL”, “GRAPH”, etc without any numeric keys are included in “Joystick + Emulated keyboard” or “Emulated keyboard” as following link.
https://docs.libretro.com/library/fmsx/#joypad-and-analog-device-type-table
So, numeric keys “1”,“2”,“3”,“4” should be included in “Joystick + Emulated keyboard” or “Emulated keyboard” to start the games (Antarctic adventure, Athletic land, etc) normally.
Please help me enjoying Antarctic adventure with PSVITA.