Newbie question about screen modes

By killimolli

Supporter (14)

killimolli's picture

17-07-2009, 08:35

Hi all,

According to BlueMSX, the Syntax Infinity demo uses various screen modes.

Screen modes are: 1,2,3,4,5 and 7.

Can someone explain what those screen modes are? I mean resolution, color depth and so on. Mode 7 is msx2 only?

Basically, this demo is msx1 demo, without that mode 7 twister?

And one demo screen that i cant figure out is that mode 4 screen, that displays 2 different "split-screen resolutions".

Yes, i know, too many stupid questions. Sorry. Im not a coder. Smile

-killimolli

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By cax

Prophet (3722)

cax's picture

17-07-2009, 09:08

Syntax Infinity demo is a MSX2 demo, it won't run on MSX1.

Screen modes are described well in this Wiki article.

"split screen" is a special technique that makes wonders possible - e.g. half-screen uses mode X, other half uses mode Y etc.

By killimolli

Supporter (14)

killimolli's picture

17-07-2009, 10:36

Mode X?

Do you mean PC mode x by famous Tran? Tran demos used to use 50hz etc frecuency. Custom resolutions and 50hz. My cheap monitor died when i ran it. Big smile

My friend EIZO monitor displayed it correctly. Those were the times!

And cax, thanks for the link. I still do not understand that mode 7 effect, because MSX CPU to VDP is sooo slow.

By karloch

Prophet (2067)

karloch's picture

17-07-2009, 10:44

Description of modes 1, 2 and 3: www.faq.msxnet.org/msx1.html#msx1gfx
Description of modes 4, 5 and 7: www.faq.msxnet.org/msx2.html#msx2gfx

By killimolli

Supporter (14)

killimolli's picture

17-07-2009, 10:58

karloch

Mode 7 CPU to VDP and vice versa speed?
Slow, really slow.

How Bore fuck up the VDP-CPU with that twister?
Just want to know technique how he raped it. It so silky smooth.

-killimolli

By NYYRIKKI

Enlighted (5441)

NYYRIKKI's picture

17-07-2009, 11:14

No, just replace the "X" with a number... Smile

To understand better, you need to understand that screen is drawn from left to right and up to down... Think about drawing a screen like reading a book...

That mode 7 effect does not require much traffic to VDP. This is same idea as in screen split where screen mode register is changed in middle of screen draw and then back on end of screen draw to make two different screenmodes visible at a same time. Only this time the trick is to change scroll register (#23) in every scanline. Very well known effect in MSX and Amiga scenes.

If you still don't get the idea, search internet for "Raster bar", this is variation of that effect.

By NYYRIKKI

Enlighted (5441)

NYYRIKKI's picture

17-07-2009, 11:21

... you can see similar effects also in demos like N.O.P - Unknown Reality and IOD - Metal limit