EGA monitor backwards compatibility (with CGA) \ VOGONS

EGA monitor backwards compatibility (with CGA)

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First post, by carlostex

Posted on 2016-09-08, 11:42

carlostex Offline

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So EGA is a digital RGBi signal with 21KHz horizontal sync signal. So if an EGA monitor also supports 15KHz signal it should also support CGA right?

I think i can get an EGA monitor for a good price but i'm wondering if back in the day EGA monitors could be used with IBM CGA cards. I don't have the specs of the said monitor yet, but i'm hoping for the thing to be able to sync into 15KHz signals, which i think would give me CGA compatibility.

EDIT: Nevermind, it seems EGA has to be dual sync, due to x 200 line modes need 15KHz horizontal sync signal. Only 350 line modes have a 21.8KHz signal.

So i guess an EGA monitor should support CGA. Is this the case with the IBM 5154?

Reply 1 of 2, by PeterLI

Posted on 2016-09-08, 12:34

PeterLI Offline

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Ask around on VCFED: lots of IBM 51** SMEs there.

Reply 2 of 2, by Scali

Posted on 2016-09-08, 14:33

Scali Offline

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Yes, EGA in 200-line mode is the same as CGA.
So an EGA monitor will work on CGA... And most EGA cards can be configured to only support 200-line mode, so they can be used with a CGA card (of course you won't have the extra resolution and colours).

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

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