how to kludge a 486 PC into thinking it has a video card?

[Randy McLaughlin]

From: "Eric J Korpela" <korpela at gmail.com>
Sent: Tuesday, February 22, 2005 12:33 PM
>> As long as you have a monitor that can handle the EGA frequency it should 
>> be
>> no great effort to use a VGA monitor on an EGA card.
>
> A couple caveats here.....
>
> 1.  Monitors that handle the frequency aren't being made much anymore.
> Most new
>    monitors won't sync below 30kHz.   Scan frequency conversion isn't
> impossible,
>    but it certainly isn't easy.
>
> 2.  EGA is a digital TTL level signal with 2 lines each for R G and B.
> When carrying
>    CGA comaptible signals the low order green is the intensity bit.
> VGA is analog
>    0.7V p-p into 75 Ohm impedence.  You need a 2-bit DAC with level
> conversion for
>    each line (which is fancy talk for a few resistors.)
>
> 3.  Beware of EGA-VGA DE-9 to HD15 adapters.  They are usually 9-pin VGA 
> to
>    15 pin VGA adapters, which is entirely different.
>
> Eric

As you and I pointed out as long as you have a monitor that can handle the 
EGA frequency it should be no great effort to use a VGA monitor on an EGA 
card.


Randy