Function 26, subfunction 3 - get CD base.
Parameters:
eax = 26 - function number
ebx = 3 - subfunction number
Returned value:
eax = CD base: 1=IDE0, 2=IDE1, 3=IDE2, 4=IDE3
Remarks:
CD base is used by function 24.
To set CD base use
subfunction 3 of function 21
.