1. Write a 1 to the SoundBlaster RESET port (2x6h)
2. Wait for 3 micro-seconds (or read six times the register port)
3. Write a 0 to the SoundBlaster RESET port (2x6h)
4. Read the byte from the DATA AVAILABLE (2xEh) port until bit 7 = 1
5. Poll for a ready byte (AAh) from the READ DATA port (2xAh). Before reading the READ DATA port it is avdvisable.

// Resets the SB DSP
// 'base_address'(in): the base address of the SB I/O ports
// 'return'(out): result code
BOOL sb_dsp_reset(WORD base_address)
{
   int	i;
   int	start_time;

   // Write a 1 to the SB RESET port
   outportb(base_address + SB_DSP_RESET, 1);

   // Wait for 3.3ms
   for(i = 0; i < 6; i++)
   	inportb(base_address + SB_DSP_BUFFER_STATUS);

   // Write a 0 to the SB RESET port
   outportb(base_address + SB_DSP_RESET, 0);

   // Read the byte from the DATA_AVAILABLE port until bit 7 = 1
   start_time = clock();
   while( (inportb(base_address + SB_DSP_DATA_AVAILABLE) < 0x80) &&
   	(clock() - start_time < SB_RESET_TIMEOUT) );

	// Poll for a ready byte (AAh) from the READ DATA port
   start_time = clock();
   while( ((i = inportb(base_address + SB_DSP_READ_DATA)) != 0xAA) &&
      (clock() - start_time < SB_RESET_TIMEOUT) );

   if(i != 0xAA) return(SB_RESET_DSP);
   return(SB_OK);
}

// Resets the SB DSP
// 'base_address'(out): the base address of the SB I/O ports if successfull
// 'return'(out): result code
BOOL sb_dsp_detect_base_address(WORD *base_address)
{
	WORD	address;

   for(address = 0x210; address < 0x290; address += 0x010)
   	if(!sb_dsp_reset(address))
      {
      	*base_address = address;
         dsp_base_address = address;
         return(SB_OK);
      }

   return(SB_DETECT_DSP);
}

// Detects the SB IRQ number
// 'irq_number'(out): the IRQ number if successfull
// 'return'(out): result code
BOOL sb_dsp_detect_irq_number(BYTE *irq_number)
{
	BOOL result;
   clock_t start_time;

   lock_memory();
   detect_install_handlers();
   dsp_irq_number = detect_irq_number = 0;

   // Trigger the interrupt
   start_time = clock();
   sb_dsp_write(SB_IRQ_TRIGGER);
   while((detect_irq_number == 0) &&
   	(clock() - start_time < SB_IRQ_DETECT_TIMEOUT));
   dsp_irq_number = detect_irq_number;
   detect_remove_handlers();

   // IRQ number -> INT number
	if(result = sb_interrupt_number(dsp_irq_number, &dsp_interrupt_number)) return(result);
   *irq_number = dsp_irq_number;
   return(SB_OK);
}