> On 2017-06-21, at 19:44, Gerrit Heitsch <firstname.lastname@example.org> wrote: > >> ... that I never used LP IRQs but thought that it would trigger only when the button line is grounded within a specific timing window so some kind of synchronisation with raster position would be required for the IRQ to happen. But that's a different subject anyway. > > No, the LP IRQ just latches the current X and Y position of the electron beam when you get the high to low transition on the LP line. And you also get an IRQ to notify you of that event. > On 2017-06-21, at 19:46, smf <email@example.com> wrote: > The VIC just latches the x & y position & fires an IRQ when it is triggered, because it assumes that if the light pen can see the gun then it must be over the current pixel. > > Adding something to VIC to ignore pulses outside the visible portion of the display would be a waste of space. But that means that I can basically trigger valid LP IRQs using joystick and pushing its fire button.. Well, as I mentioned, I never wrote a single instruction to serve any lightpen support. -- SD! - http://e4aws.silverdr.com/ Message was sent through the cbm-hackers mailing listReceived on 2017-06-21 19:00:03
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