strange register writes with iodumper

[cyberic99]

When using the iodumper plugin on the following file, I get some strange register writes:

For instance:

0000d240 ffd0=01
00000100 ffd0=02
00000198 ffd0=03
000001b8 ffd0=04
00000138 ffd1=0a
000001b4 ffd5=02
00000074 ffdf=00
0000f850 ffd0=01

DMG-MLA.gbs.zip

is it expected to write to invalid registers or to registers not related to sound?

In this file, when playing track 1 in loop for 3 minutes, there are 14887 useful register writes, and 79897 invalid ones.

I wonder if gbsplay should filter them out.

Thanks

[ranma]

ff80-fffe is actually a RAM area (normally used as stack), so that should be skipped in the iodumper.