Disable Video Card

Adding a new video card to your AT&T PC 6300

OK, so just about all of us 6300 users have realized that although the video card in the machine was cutting edge at the time, and is still great today, it is a little limiting. Perhaps you don’t have a working AT&T monitor anymore? Well its not like you can just hook up an IBM monitor--the AT&T video card is proprietary!

Simple solution would be to just replace the video card. Some thought it to be impossible, period, or that you must have a P8 revision video card. Not so! By disabling a setting on the motherboard, adding a new video card, and plugging it all in, the sometimes pesky AT&T video card will no longer be an issue. YOU MUST HAVE ROM 1.43 OR HIGHER FOR THIS MODIFICATION TO WORK!!!

First step is to remove the bottom cover. Clear your work surface and lay down a soft cloth as big as or bigger than the AT&T PC 6300 system unit. This is not necessary, but will prevent the careless damage of your AT&T’s paint. Place the AT&T PC 6300 upside down on the work surface, with the rear facing yourself or whoever is working on the unit.

Remove the bottom cover by unscrewing the screws holding on the bottom cover. In the position that the AT&T PC 6300 should be in, you will find these screws at the top left and right of the case(which is ACTUALLY the bottom of the case, but the unit is upside-down, remember?). These screws will not come totally out. Instead, they will hang somewhat lazily from their holes.

Now that you have the case open, it’s all cake from here. On Dip-switch block 1 (switch set closest to the rear of the unit. If the rear of the unit is closest to you, then so will Dip-switch block 1) you will need to change the settings as follows depending on the video card you are adding:

EGA/onboard video disabled: SW5--On SW6--On

40 X 25 color: SW5--Off SW6--On

80 X 25 color: SW5--On SW6--Off

80 X 25 mono: SW5--Off SW6--Off

The color settings will work with any ROM revision. The switch controlling the video is only listed on ROM 1.43 or higher. On others, the use is marked as “for future use.” The mod MAY work on ROM 1.23 or lower despite it not being listed. If you try and it works, let me know. The rest is simple. Just add in the card of your choice--I added a genuine IBM MDA card. The printer port on it became LPT2.

Enjoy! Please link my site as many times as you can when you can and where you can. Just don't spam my site around giving me a bad rep.