Hi!
I have this player
http://blurried.free.fr/PMP/SPMP3050A.jpg
I've extracted the firmware and in aimg have a 3050ABin0.bin file
When I examine this file with a hex editor I find a lot of references to a internal libraries. The strange thing is that a lot of this have the same name of windows libraries and, internaly, the mem (internal and expanded by SD) are referenced like unit C: and D:!!!
May be a windows/DOS like SO???
Definitly is not an unix derivate!
PD: A: and B: are the aimg and bimg and C: and D: are the internal and sd mem
PD2: some internal calls ARE VERY SIMILAR to a Visual Basic file edited in hex form
PD3: There are some references to C too
PD4: ...mmm...definitely is C!!