What does this flashing number means?
 

http://eab.abime.net/attachment.php?...1&d=1609036931\

edit: What I mean is the number 66, I didn't screenshot it during when it flashed

That number is the track of the DF0: disk which is read :)

ah okay, thank you for answering my question.

You are welcome :xmas

ADF, ADZ, DMS files are disk images (not ROMs)..so when you insert the virtual floppy disk (not ROM), you get to see which track is being read (not sectors). If you enable the sound for floppy drive access you'll get hear it being accessed as it was back in the day..and how real hardware does stuff. :)

Other less common disks images : COP, ZOM, ZAP, DSQ, WRP :)