[comp.sys.ibm.pc] Creating new EGA/VGA modes

desmond@smaug.dec.com (President, LKG Sunset Club) (11/10/88)

I would like to use IBM EGA and VGA cards in modes which are not
supported by the BIOS.  Specifically, I'd like to be able to set
them into something on the order of 720 by 400.

Can I do this if I just set appropriate values into the CRT Controller
registers?

Is there any danger in doing this (i.e. is it possible to destroy
monitors or cards when doing this?)

Any helpful information about programming EGA and VGA cards for
custom graphics modes would be appreciated also.  Thanks.

						John
ARPANET:  desmond@smaug.dec.com

bkliewer@iuvax.cs.indiana.edu (Bradley Dyck Kliewer) (11/11/88)

In article <8811101454.AA28625@decwrl.dec.com> desmond@smaug.dec.com (President, LKG Sunset Club) writes:
>I would like to use IBM EGA and VGA cards in modes which are not
>supported by the BIOS.  Specifically, I'd like to be able to set
>them into something on the order of 720 by 400.
>
>Can I do this if I just set appropriate values into the CRT Controller
>registers?
>
>Is there any danger in doing this (i.e. is it possible to destroy

While writing _EGA/VGA A Programmer's Reference Guide_, I was reprogramming
the CRTC registers quite frequently.  The ECD monitor on my primary development
system burned out recently, but I don't know whether it was related (I've seen
comments from several others that this monitor is prone to failure after a 
few years of continuous use).  However, I would be _very_ careful.

Getting all of those registers set to the correct values is pretty tricky,
too -- but you may already realize that.

Bradley Dyck Kliewer                Hacking...
bkliewer@iuvax.cs.indiana.edu       It's not just an adventure
                                    It's my job!