This is a game where the BBC version in my opinion has faster and better scrolling than the CPC version. Other CPC games may have worse scrolling than Uridium, my point was that the CPC could have had the same scrolling as the BBC. Same graphic chip. Maybe a 6502 instead of the Z80 would have been better after all. The BBC coders could have jumped over to the Amstrad CPC. We would still get ports, but from the C64 instead.
I agree. The only difference between BBC and CPC is that I think when the BBC scrolls horizontally it's in 1 byte units compared to 2 bytes on CPC. The way the BBC maps the memory addresses to the screen is different.
On CPC, incrementing by a byte moves accross one byte to the right. I believe on the BBC it moves 1 line down. 8 increments moves down 8 lines and then to the start of the next crtc char to the right.
But you are correct, same CRTC, same features, and the BBC has to draw and erase it's sprites by software methods.
I think it's 2Mhz 6502 means it ends up faster than the CPC, but it's native display size is bigger (20K or so compared to 16K).
I think Uridium was meant to be fast and smooth and responsive. On the CPC the current version needs a little bit more speed and tweaking.
BTW, I am continuing with my "journey into CPC hardware scrolling" with more examples and more documentation.
More updates soon. (It's also helping to 1) cement my knowledge and help he with the beat em up game 2) I am actually testing some of the methods I've seen being used for myself to verify and show others what can be done).