CURSOR signal on CPC expansion port

[TFM]

Well, the PlayCity uses the CURSOR signal on the CPC Expansion port...

But how does it work?

When does the CURSOR signal get's switched ON/OFF?
How can it be influenced by the CRTC registers?

@TotO, anybody?

[TotO]

There is a CURSOR example on the PlayCity page. Its work is close to the L.PEN signal.
You enable it by defining a scanline size greater than 0, then you move it where you want.
Each time the CRTC display the screen and have to "render" it, the CURSOR signal goes LOW.
On the PlayCity, this signal trigger an INT so you can use it to manage a real pointer or use your routine to make accurate raster effects.