The PIV has a flickerfixer/scandoubler card built onto it, which is about the size of a Concierto, which has to be broken off. It's perforated as much as a circuit board will allow, but it still needs to be taken off with a hobby knife very carefully.
There's a ribbon cable which connects to the PIV and then runs across the 2000, over the power supply and connects to the FliFi/ScanDoubler, which goes in the video slot.
I wouldn't want to, but after it's been broken off it can still be used in a 4000, You'd just need the ribbon cable all the time.
