The name "VFS Utilities ROM" might sound a bit general for the rather specific function that it performs. The explanation is that eventually I would like to put a few more bits and pieces in this ROM, but I haven't got round to them yet.

I need to make another point here, because users of the proper Domesday System will no doubt be thinking that this is all totally pointless since superimpose mode is automatically selected when you've got one of the Domesday Discs in the drive and you press BREAK.

That's true up to a point, but only if VFS is configured as the default filing system, and VFSDir (the same effect as ADFS's Dir option) is set as the configuration setting. The reason for this is that with those configuration settings, VFS will attempt to mount the disc when BREAK or CTRL-BREAK is pressed, just the same as ADFS does in the same situation. In doing so, VFS issues a Start Unit command to the LV-ROM player. This causes the VP415 to select several options, including setting the video mixing mode to superimpose.

However, this doesn't happen if VFS isn't the default filing system, or if it's not the currently selected filing system immediately prior to a soft reset. My own Domesday Machine isn't set to VFS as the default filing system, as you can see in the picture above and as is confirmed in the Status listing we saw earlier in this picture set. In those circumstances, the ability to set the video overlay mode as a configuration option is very useful.

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