Well, pkunzip e.g. exits with "divide by zero" error.
Guess why...
Looking at the handler for int 29h (CB_INT29 part) I find

1                phys_writew(physAddress+0x01,(Bit8u)0x0eb4);    // mov ah, 0x0e
2                phys_writew(physAddress+0x03,(Bit8u)0x10cd);    // int 10

Not a good idea casting this into some 8 bit type...