> Von: "Marko MÃ¤kelÃ¤" <email@example.com> > Can the 6522 VIA generate interrupts? Even if it cannot, you could use > the VIA timers to simplify the cycle-counting. Yes, the VIA can do interrupts. > On the PET, if there is no readable raster line counter in the 6545, I > guess you would need a trick that uses the IRQ line for determining when > exactly the vertical blank interrupt is being triggered. Then, you would > set up some sort of a delay loop in the "main program" and wait for N > more vertical-retrace interrupts to eliminate the horizontal jitter. No, the 6545 does not have a readable raster line counter. In fact none of the registers you can write to can be read (IIRC) And I have done that IRQ handling in my test programs at http://www.6502.org/users/andre/hwinfo/crtc/pet/index.html - on the vertical irq set the VIA timer and then on VIA interrupt change the CRTC registers. AndrÃ© -- NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone! Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a Message was sent through the cbm-hackers mailing listReceived on 2012-04-26 20:00:05
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