js9b+@andrew.cmu.edu (Jon C. Slenk) (12/10/88)
Ok. I have a slight problem concerning raster interrupts with the 64. The program I use now wedges itself into the IRQ that happens every 60/50th of a sec. It checks to see if the cause was the raster line position. If it is, it goes to my routine... ...the point is that my scrolling routine is a little wierd at times. I want to set the line position to the very end of the screen so the scrolling takes place off screen (ie before the raster line comes back round again). My program will either a) change the y scroll bit or b) reset it and copy the screen text one line back. The thing is that I want to set the interrupt line at the end of the screen. As I approach the end of the screen, the thing seems to time out: the scrolling is going along fine for a while and then freezes. The closer I get to being at the end of the screen, the sooner it freezes, as though the interrupt line was creeping up and then off the screen, and thus the machine never gets to that raster line (>320 or whatever - the msb has been set) and so doesn't scroll. I am probably being totally unclear. If you have any info on this, or if (better yet) you actually understood what I am attempting to say, then PLEASE help. THANK YOU!! Sincerely, Jon Slenk / js9b CMU.
fred@cbmvax.UUCP (Fred Bowen) (12/14/88)
In article <AXc3X7y00Xo8A3GlBH@andrew.cmu.edu> version B 2.10.3 4.3bsd-beta 6/6/85; site cbmvax.UUCP cbmvax!rutgers!rochester!pt.cs.cmu.edu!andrew.cmu.edu!js9b+ js9b+@andrew.cmu.edu (Jon C. Slenk) writes: >Ok. I have a slight problem concerning raster interrupts with the 64. > >The program I use now wedges itself into the IRQ that happens every 60/50th of a >sec. It checks to see if the cause was the raster line position. If it is, it >goes to my routine... >Jon Slenk / js9b CMU. It sounds like interrupts are interrupting your interrupt handler, eventually overflowing the stack and crashing. That, or you are not properly clearing interrupt, or you are taking an awful long time to scroll the screen. -- -- Fred Bowen uucp: {uunet|rutgers|pyramid}!cbmvax!fred arpa: cbmvax!fred@uunet.uu.net tele: 215 431-9100 Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380