I too wanted more video RAM to make things easier. It was a no. You can find the reasons somewhere in this forum.
So I made a spreadsheet to do some calculations and comparisons between some different combinations of screen modes, layer sizes and bit depths to see what the X16 could do and what I have to work with.
One example:
Resolution: 320x240
Layer 1: 128x32
Layer 2: 64x32
Colour depth: 8bpp
If my calculations are correct there is enough memory to have over 1700 8x8 or equivalent images, for either tiles or sprite animations.
Using the 4 orientations (normal, H-flip, V-flip, H+V-flip) that’s a lot of images to build a screen and for animations.
Using 4bpp with a custom palette and palette offsets could massively increase that number.
15 hours ago, svenvandevelde said:
What I don't like is the lack of sufficient VRAM in the VERA. Even in 4bpp, memory runs out fast. Especially if you want to embed spritee animations. With the hardware capabilities of the VERA, memory is underscaled when using the high resolution 640x480 in tiled mode.
An example ... 12 sprites of 32x32 pixels in 4bpp requires $1800 bytes. But in high resolution 32x32 px is very little. 64x64 px quadruples the memory requirement... then you talk about $6000 bytes. And that is for just one "healthy" sprite animation ... beside that, you need explosions, damaged states, shadows, overlays like glowing effects, bullet types. So per enemy type you can easily consume $8000 to $A000 bytes (when in 64x64). And note that all this is in 4bpp. When using 8bpp that requires a multiple by 2. So 12 sprites in 8bpp 32x32 consumes about $3000 bytes. In 64x64 mode that would be $C000. That's 1/3 of the VERA VRAM, for one healthy enemy.
An interactive arcade game would easily have 6 to 8 different enemy types on the screen requiring animations, damage states, bullets, shields, glowing etc.
Noting that the VERA has 128 different sprites that can be shown simultaneously I really am afraid that memory upscaling is a requirement to use the full potential of the machine.
16 hours ago, x16tial said:
Are you using all 255 banks of RAM? Data can be copied into and out of VERA memory.