how to disable shared memory?

No; yes, but only as a secondary (you can't use it as a primary display), and they're very expensive (figure in the $500 range) and usually based on old, 2-d (Rage Pro) chipsets.

what you mean "primary/secondry"? there is not any option in my bios.
can you give a link that sell PCMCIA graphic card?

Secondary means you can't use the PCMCIA card for boot video.

This is about the only PCMCIA card maker left for video:

http://www.villagetronic.com/