Function 21, subfunction 4 - set Sound Blaster base port.
Parameters:
- eax = 21 - function number
- ebx = 4 - subfunction number
- ecx = number of the base port
Returned value:
- eax = 0 - success
- eax = -1 - erratic port number
Remarks:
- Number of the port must satisfy to conditions 0x100≤ecx≤0xFFFF.
- The installation of the base is necessary for
functions 25, 28, 55.
- To get base port use subfunction 4 of function 26.