screen resolution OCS/ECS/AGA

[Tiago]

What is the screen resolution of an Amiga Game NDOs ?

i know workbench can have different screen resolutions, i guess games under workbench can also have some different resolutions, but what i am asking is the traditional NDOS games,

what resolution they use? OCS and AGA? are there may games done for ECS?

[Phantom]

Games use the standard PAL or NTSC (depending) resolutions.

OCS/ECS/AGA PAL
320 x 256 (low-res)
320 x 512 (low-res interlaced)
640 x 256 (hi-res)
640 x 512 (hi-res interlace)
704 x 576 (overscan)

Colors are from 2 up to 4096 using HAM mode. There's also the EHB (Extra Half Brite) mode which has 64 colors (actually it's 32 colors but their colored pixels are halved). That's for OCS/ECS.

Normally games had 32 colors in low-res mode which is the maximum, and 16 colors in hi-res mode which is the maximum too. That's for OCS/ECS.

The same applies to AGA which introduces 256 colors instead of 32 colors, as well as HAM8 mode which can have up to 16,7 million colors.

To sum it up, almost all games under OCS/ECS mode use low-res resolution with 32 colors (very few with 64), and very few also in hi-res mode.

On the other hand, games under AGA mode use low-res resolution with 256 colors instead.

[Tiago]

Thanks Phantom, great info.

[Harrison]

Great summary Phantom.

Some small additions regarding colour.

With OCS/ECS the HAM mode utilises and can display the total available system palette of 4096 colours on screen at once. With AGA HAM8 it can display 262K colours from a palette of 16.7 Million colours, so not the complete palette at once, but even so, 262K colours is more than enough for most images.

[Phantom]

Thanks for the correction Dave.

[Harrison]

Interestingly, I also read that HAM8 might not actually be restricted to 262K colours. This is based on resolution and other factors. In fact, some have reported that using an Indivision flicker fixer and its own screen modes it should be possible to display over 800K colours on screen at once. Most interesting.

There is also something called SHAM, SuperHAM or more technically known as SplitHAM. This was developed by the Demoscene for OCS/ECS machines and uses the copper to renew the palette ever scanline of the screen redraw in HAM6 mode, allowing a complete palette switch for each line of the screen, in theory allowing full 4096 colour modes in higher screen resolutions than HAM6 is normally restricted to.