Is there a consensus on the best way to detect a C128 from C64 mode? I was thinking of using the 80col VDC registers, which are visible in C64 mode.
I was discussing doing this to switch the CPU to 2Mhz (by setting bit 0 of $D030) during vertical border/refresh for some C64 programs, using raster interrupts.
Many CPU intensive programs could benefit from this, my own checkers/board game programs, but also other games, 3d demos etc. Its a very simple "free" speedup of about 30% or so.
If you are prepared to reduce the screen area, you can get up to 80% speed up. For example a board game (chess , checkers etc) could show a small 8 char high board/screen when thinking, then the large board when its the players turn. 3d demos often only render a small screen area to get a good frame rate, etc.
I was discussing doing this to switch the CPU to 2Mhz (by setting bit 0 of $D030) during vertical border/refresh for some C64 programs, using raster interrupts.
Many CPU intensive programs could benefit from this, my own checkers/board game programs, but also other games, 3d demos etc. Its a very simple "free" speedup of about 30% or so.
If you are prepared to reduce the screen area, you can get up to 80% speed up. For example a board game (chess , checkers etc) could show a small 8 char high board/screen when thinking, then the large board when its the players turn. 3d demos often only render a small screen area to get a good frame rate, etc.
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