Does anyone know if the upper 4 unused bits of the EDL register are read back as written? I can't find any documentation that says one way or another and it's possible there could be some random game that relies on this for some odd reason (or relies on it always reading back as 0 or some such nonsense).
Anomie's apudsp.txt doesn't say either way. Which is a little strange because it does say that the upper 2 bits of the VxPITCHH register ($x3) are "read back as written". So does the absence of a similar comment for the EDL register mean that they are not? However, it also doesn't say that they read back as some static value (e.g. 0). But I don't think that's the case because if a bit always reads back as 0 then anomie puts a '0' in for that bit (see VxENVX for example).
Anomie's apudsp.txt doesn't say either way. Which is a little strange because it does say that the upper 2 bits of the VxPITCHH register ($x3) are "read back as written". So does the absence of a similar comment for the EDL register mean that they are not? However, it also doesn't say that they read back as some static value (e.g. 0). But I don't think that's the case because if a bit always reads back as 0 then anomie puts a '0' in for that bit (see VxENVX for example).