Posted By
MMS
on 2023-03-26
04:14:48
 |  Re: Elite +4: Circle Closes
@Pigmy and @Csabo
Well, guys you know the details.
Knowing the exact differences and similarities between the two machines could help a lot in the conversion process. With the SVS Ultimate map, this part is almost completely covered, though in the 80s and 90s such lists were hardly available.
But there are other details may block the "average user" to start his process, and it means me 
Certainly the biggest challange is the sprite, and I do not want to go to these details, that's why arcade game creation is more complex on our system.
Pigmy, you wrote it down when you was 15 yo, how you did the sprite cursor of Tass Times with the help of raster, but it was "in chinese" for me at that time, and I did not grow to that level since then
Let's take an other simple challange, and adventure with graphics, drawn by the game, like The Hobbit. (certainly the "only text" adventures does not mean a real challange, if I know the different character map and color map addresses, and we have the proper color conversion table (also available now)). that's why we have so much on Plus/4.
But the question came up: when you have a Hires/MC draw routine in the C64 original game, it will draw the bitmap lines and at the same time puts the proper colors to the C64 color map. On the other hand, on Plus/4 you have to add the luminance too. So at least an additional 5 bytes you need to squeeze into the original code. So it is NOT simply changing few memory addresses, but you need to change the original code (except you fill up the luminance table with a fix values may fit for the C64 colors).
If you increase the size of the code in the memory, then everything else need to be shifted, and it may overwrite other important elements in the game.
So that's why I was so surprised you could do all these in the built-in TED monitor. And that's why I believe that usually it is not enough to blindly change the addresses :-)
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