Posted By
Stinaris
on 2017-01-14
03:37:38
 |  Re: VB interrupt. How do you get it to trigger?
Thanks for your replies.
Sorry for my vague post. I'm actually writing for the C16. I really fancy a challenge. I had to abandon one game as I basically ran out of memory just generating the graphics and one game engine. So I decided to choose a game with a single game engine.
Currently I'm using address $0314/315 to generate my raster interrupts scrolling only the top 20 char lines with the score in the bottom 5 lines. Sadly the processor doesn't have the grunt to shift 800 chars without tearing so I doubled buffered the screen and colour memory in $0c00/$0800 and $3400/$0300 respectively.
So I would like to shift the buffer during the vertical blank so I set the vectors in $0312/0313 as it looked like the obvious choice but there is no specific enable flag which led me to assume that it would use the same flag as the raster.
The plus/4 programmers reference manual is quite good but lacking compared to the c64 version.
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