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Why does VGA only support 320x200?

Topics: Developing Cosmos (Working on Cosmos source code directly)
Sep 19, 2012 at 6:53 AM

This has always puzzled me. Why does our VGA Drive only work with 320x200 mode? When its supposed to be able to do 400x300 and 800x600? Is this a Cosmos bug, or a bad driver? Thanks Matt. This has always interested me.

Sep 19, 2012 at 8:18 AM

I believe the original VGA controllers only allowed 320x200

On Sep 19, 2012 3:24 PM, "civilwarrock" <notifications@codeplex.com> wrote:

From: civilwarrock

This has always puzzled me. Why does our VGA Drive only work with 320x200 mode? When its supposed to be able to do 400x300 and 800x600? Is this a Cosmos bug, or a bad driver? Thanks Matt. This has always interested me.

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Sep 19, 2012 at 8:37 PM
Cman332 wrote:

I believe the original VGA controllers only allowed 320x200

On Sep 19, 2012 3:24 PM, "civilwarrock" <notifications@codeplex.com> wrote:

From: civilwarrock

This has always puzzled me. Why does our VGA Drive only work with 320x200 mode? When its supposed to be able to do 400x300 and 800x600? Is this a Cosmos bug, or a bad driver? Thanks Matt. This has always interested me.

Read the full discussion online.

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Is SVGA a Standard like VGA? Thanks, -Matt

Sep 19, 2012 at 9:50 PM
civilwarrock wrote:
Cman332 wrote:

I believe the original VGA controllers only allowed 320x200

On Sep 19, 2012 3:24 PM, "civilwarrock" <notifications@codeplex.com> wrote:

From: civilwarrock

This has always puzzled me. Why does our VGA Drive only work with 320x200 mode? When its supposed to be able to do 400x300 and 800x600? Is this a Cosmos bug, or a bad driver? Thanks Matt. This has always interested me.

Read the full discussion online.

To add a post to this discussion, reply to this email (Cosmos@discussions.codeplex.com)

To start a new discussion for this project, email Cosmos@discussions.codeplex.com

You are receiving this email because you subscribed to this discussion on CodePlex. You can unsubscribe or change your settings on codePlex.com.

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Is SVGA a Standard like VGA? Thanks, -Matt

SVGA stands for Super VGA, the reason why is because each video card has different specifications (so you basically need a driver for every possible video card, not that easy :( ). The BIOS however offers limited functions (VESA BIOS Extensions) but requires the OS to communicate with the BIOS and since cosmos is in protected mode it can not. However it is possible to switch into real mode temporary, call a BIOS function then return to protected mode but that slows down the OS.