Specifications

Introduction to DSP Programming 2-7

The byte from register 81h is interpreted as follows:

D7 D6 D5 D4 D3 D2 D1 D0

DMA

where the grayed areas denote reserved bits.

To configure the DMA channel settings, set the corresponding interrupt bit to '1' to

select the DMA channel. Note that only a bit on the 16-bit DMA channel (DMA5,

DMA6 or DMA7) can be set on at any one time. This applies for the 8-bit DMA

channel (DMA0, DMA1 or DMA3).

DSP version 4.xx also supports the transfer of 16-bit digitized sound data through 8-

bit DMA channel. To make this possible, set all the 16-bit DMA channel bits to '0'

leaving only an 8-bit DMA channel set.

Note that application should not write to these registers to change the DMA and

interrupt settings as many other system configurations such as BLASTER

environment and Windows SYSTEM.INI file need to be updated when changing

these registers. These registers should only be changed by system software such as

SBCONFIG.EXE that come with Sound Blaster 16 package.

NOTE : Registers 80h and 81h are Read Only for PnP boards.