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

From: Jim Leonard <>
Date: Mon Feb 21 10:29:16 2005

On Sun, Feb 20, 2005 at 02:17:32PM -0800, Steven Canning wrote:
> > > Far as I know the BIOSes of the time would check for MDA / CGA / EGA /
> > > VGA adapters at boot time, but 'not fitted' wasn't usually an option. I
> > > wonder if there's a clever way involving a minimum of circuitry in such
> > > a case for the BIOS checks to work...
> Why not just through a $2 Hercules Graphics card in an ISA slot and be done
> with it ? For troubleshooting you can spew graphics or text if needed....

I have to agree with this, although I'd recommend an ISA VGA card instead
of CGA/EGA/Herc (because the latter are harder to find, worth more to
collectors, etc.). ISA VGA cards are so plentiful you can pick them up
for $1 a piece on ebay (ie lots of 10 that sell for $10 + shipping).

The only way to hack a BIOS to not halt on NO VIDEO errors is to...
hack the BIOS (ie desoldier the chip, read EPROM, adjust code, write
EPROM, soldier chip). $1 per machine definitely falls under the
"time is money" rule.
Jim Leonard        Email:
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Received on Mon Feb 21 2005 - 10:29:16 GMT

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