YMF721 datasheet(16/41 Pages) LSI

16 / 41 page

YMF721

July 10, 1997

- 16 -

6-3-2. Resume

Command and Response have the following formats.

For Resume, data following the sub command are transmitted as seven bit data. Thus, it is necessary

to send the data obtained with suspend command to the internal processor after encoding it.

Checksum is determined so that the result of logical product (AND) of 7Fh and the sum of sub

command byte, encoded data and checksum becomes "0". The internal processor returns to the state

immediately before execution of Command E0h when it confirms that the data has been received

normally.

6-3-3. Others

YMF721(OPL4-ML2) can use the following special commands that do not send response.

1) Command FDh : Power down mode

Refer to 5-1.

When the power down command FDh has been written into the command register, do not write

any command before the return command to the control register has been executed.

2) Command FEh : Checking operating state of internal processor

This command is used to check if the internal processor is operating normally.

The internal processor is deemed operating normally if GBUSY bit of Status register is "0".

3) Command FFh : Discontinuing command execution

This command is used to discontinue the execution of a command. This command can be used

only when another command is being executed.

Command

Response

E1h

Command byte

None

0x00

Sub Command

data_0

data

..........

.......

data_n

last data

checksum

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