When interacting with
Hardware-components of your
computer by writing to specific
memory
adresses, this is called
memory mapped IO. Sending a command to your
soundcard (i.e. writing a value in one of its registers) is simply done by
writing to a memory location.
volatile char * foo = 0xDEADBEAF; // 1 byte register maped to memory location 0xDEADBEAF
*foo = 0x00; // initialize the register
do not forget to use
volatile pointers for that.