IOS0 & IOS1 sets the base I/O address as follows 
IOS0 On IOS1 On Base I/O address 220 
IOS0 Off IOS1 On Base I/O address 240 
IOS0 On IOS1 Off Base I/O address 260 
IOS0 Off IOS1 Off Base I/O address 280 
MSEL sets the MPU-401 Midi Port address On MPU-401 address 330 Off MPU-401 address 300 
ISO & IS1 sets the interrupt line 
IS0 On IS1 On Sets the interrupt to 2 
IS0 Off IS1 On Sets the interrupt to 5 
IS0 On IS1 Off Sets the interrupt to 7 
IS0 Off IS1 Off Sets the interrupt to 10 
DAS0 & DAS1 sets the 8-bit DMA channel 
DAS0 On DAS1 On Sets the 8-bit DMA channel to 0 
DAS0 Off DAS1 On Sets the 8-bit DMA channel to 1 
DAS0 On DAS1 Off Sets the 8-bit DMA channel to 3 
DBS0 & DBS1 sets the 16-bit DMA channel 
DBS0 On DBS1 On Sets the 16-bit DMA channel to 5 
DBS0 Off DBS1 On Sets the 16-bit DMA channel to 6 
DBS0 On DBS1 Off Sets the 16-bit DMA channel to 5 
JYEN enables or disables the Joystick Port 
On Joystick Port Enabled 
Off Joystick Port Disabled 
MPUEN (MFBEN) enables or disables the MPU-401 Midi Port 
MPUEN On MPU-401 Midi Port enabled 
MPUEN Off MPU-401 Midi Port disabled 
IFSD & APSD enables or disables the Creative Advanced Signal Processor 
Both Off Advanced Signal Processor enabled Both On Advanced Signal Processor disabled 

-- MattWalsh - 05 Jul 2003