YMF754-R datasheet(39/60 Pages) YAMAHA

39 / 60 page

YMF754

June 28, 1999

-39-

2-2-3. SB Suspend / Resume

The SB block can read the internal state as to support Suspend and Resume functions.

The internal state

is made up of 268 flip flops.

To read the state, these states are shifted in order and read 8 bits at a time

from the SCAN DATA register.

These registers are mapped to the SB Mixer space (see SB Mixer Register map).

The registers have the

following functions.

F0h: Scan In/ Out Control

Read / Write

Default: 00h

SBPDA

SBPDR

b0................SBPDR: Sound Blaster Power Down Request

This bit stops the internal state of the Sound Blaster block.

“0”: Normal

(default)

“1”: Stop

b1................SE: Scan Enable

This bit Shifts the internal state by 1 bit.

Setting a “1” followed by a “0” shifts the internal state.

b2................SM: Scan Mode

This bit sets whether to read or write the state.

“0”: Write

(default)

“1”: Read

b3................SS: Scan Select

This bit gives permission to read or write the internal data to the SCAN DATA register.

“0”: Normal operation (Do not allow read or write).

(default)

“1”: Allow read and write.

b7................SBPDA: Sound Blaster Power Down Acknowledgement

This bit indicates that the SB Block is ready to read or write to the internal state after setting SBPDR.

This bit is read only.

“0”: Read/Write not possible

“1”: Read/ Write possible

YMF754-R Datasheet(PDF) 39 Page - YAMAHA CORPORATION