Mega Drive questions

[kremiso]

Originally Posted by saimon69

Improve = rewrite almost from scratch for native HW in assembly in this case

really, so drastic?
the md code seems almost 100% standard C language (at least Github says so)

I wasn't thinking it would require something close a complete restart

[saimon69]

Originally Posted by kremiso

really, so drastic?
the md code seems almost 100% standard C language (at least Github says so)

I wasn't thinking it would require something close a complete restart

If is done using SDL then i know jotd did some wrapper for it but not sure on the final performance - graphics might need some adaptation though

[PortuguesePilot]

Originally Posted by saimon69

If is done using SDL then i know jotd did some wrapper for it but not sure on the final performance - graphics might need some adaptation though

The A500's lowly 7MHz M68000 isn't very keen on pure C either... Performance would suffer. Yes, I know the MD has a 7.16MHz M68000 but in the console's case much of the churning on the graphical department would be made by the VDP (which has chunky mode, lacking on the OCS and even AGA, with all the known consequences).

[kremiso]

thank you for the tech explain guys

i'm trying to find some con/slowdown in that md port, none until now
all the enemies in the egg corridor are there
maybe it will suffer in the big boss battles
still, impressive job

if it will appear on the c64 in future, i'll quit the miggy scene
joking ofc

[saimon69]

Originally Posted by kremiso

thank you for the tech explain guys

i'm trying to find some con/slowdown in that md port, none until now
all the enemies in the egg corridor are there
maybe it will suffer in the big boss battles
still, impressive job

if it will appear on the c64 in future, i'll quit the miggy scene
joking ofc

Well, Cave Story is A BIT more intensive than a Sonic, even with the MRU - is a borderline metroidvania and some boss are kinda big - the 64 can do it with some tricks - the megadrive use its 80 sprites and three tiles (characters) layers, we could likely do it in 16 colors, 25FPS, one hard disk and one megabyte of RAM but adjustments will need to be done

[Bruce Abbott]

Originally Posted by saimon69

Well, Cave Story is A BIT more intensive than a Sonic, even with the MRU - is a borderline metroidvania and some boss are kinda big - the 64 can do it with some tricks - the megadrive use its 80 sprites and three tiles (characters) layers, we could likely do it in 16 colors, 25FPS, one hard disk and one megabyte of RAM but adjustments will need to be done

Sure. But looking at the example screenshot I wonder why we would bother.

[kremiso]

Can agree here
a lot of work to have another so so port... no thanks

was reading this page with some differences from the md and the pc version, with some tricks used too :

https://github.com/andwn/cave-story-...DIFFERENCES.md

[idrougge]

Originally Posted by Bruce Abbott

Sure. But looking at the example screenshot I wonder why we would bother.

Because it’s an excellent game, one we would be proud of if it originated on the Amiga.

[WayneK]

Originally Posted by saimon69

Well, Cave Story is A BIT more intensive than a Sonic, even with the MRU - is a borderline metroidvania and some boss are kinda big - the 64 can do it with some tricks - the megadrive use its 80 sprites and three tiles (characters) layers, we could likely do it in 16 colors, 25FPS, one hard disk and one megabyte of RAM but adjustments will need to be done

Just to be clear, the megadrive only has 2 tile layers (called ScrollA and ScrollB respectively) not 3.

[masteries]

Megadrive / Genesis video hardware is designed as an arcade system; all is 4 bit chunky mode tile based, and sprites and map tiles are managed as hardware sprites. (Maps are a bit different, but hardware internals drawing method is almost the same).

Thanks to 4 bit chunky mode, and 16 bit accesses, for each accesed data, the graphical powerhorse always retrieve 4 pixels of graphic data (including no displayed colouerd pixels). These accesses are DMA based at 13 MHz.


This approach has many advantages and some disadvantages, such you are usually limited to the hardware constraints; such tiny video RAM.


But good framerates and possibilities to display dozens of sprites and detailed maps are guaranteed, for little CPU cost.