onlyonemac wrote:
Try pushing everything to the stack before calling the BIOS function and then popping it afterwards. If this works then I'm guessing that the BIOS function is corrupting a register that you aren't expecting it to. Check the documentation for the function that you're using and see what registers are supposed to be preserved, if you're expecting it to preserve registers that it isn't supposed to preserve then it's possible that it might work on some BIOSes that happen to preserve those registers but not on others that don't, otherwise your BIOS is evidently corrupting a register that it's supposed to preserve.
Im a bit new in ASM, you push every register before calling the function, and then once I entered in for example printc or newline; pop all the registers?
Yes.