[Coco] Becker interface for Coco 2 emulators

[Robert Gault]

I am running MESS and VCC on a WindowsXP system. MESS and MAME should be essentially the same but I 
can't test that.

The ROM that works with VCC, MESS Coco3, and MESS Coco2B (even though it says Coco3 with Coco2B) is 
hdbdw3bc3.rom from the Toolshed3 project. Keep in mind that this ROM has a $000000 byte offset at 
$D938. If you want to use .vhd disk images in Drivewire, you should change the offset to $5A000.

Robert