6.11 Hard check command

Below are the details of the check performed by the hard check (89h) command. When checking, the command parameter P1 specifies a value from 0 to 5, and the following check is performed according to the value. The following values ​​are stored in the system interface table (address 418h: word) for all check results.

7FFFH: Memory check Error
8000H: Memory check Ok 

P1 value	What to check
00h	Executes read / write check of sound D-RAM (4M bits). Note that the DSP is initialized at this time to disable internal memory access. Checks write & read & compare all bits low / high, and the result is stored in the system interface table.
01h	Executes read / write check of sound D-RAM (8Mbit). Others are as described above.
02h	Check the operation of the SCSP built-in MIDI. At this time, please short-circuit the external MIDI input / output terminal . The result of the check is as described above.
03h	A square wave is output from the LR. Note that SCSP slot 025B00000H is forcibly used at this time. This sound is automatically turned off in a few seconds. In addition, Map data, song data, and timbre data are not required for issuing this command.
04h	A rectangular wave is output only from the L side. Others are as described above.
05h	A square wave is output only from the R side. Others are as described above.