Normally you can only add 128MB RAM to bring it up to 256MB.
Some "expert" elsewhere claims you can go beyond that and only gullible Americans believe you must stay within company limits.
Okay, let's see- I'm not going to say it CANNOT be done but the base memory is 128MB. If you add a 256MB chip you would have 384MB. 512MB would make 640MB.
Those are pretty weird numbers.
AND- it assumes at the very least the new chip would physically fit inside the laptop.
Is this possible? I am curious about how far old hardware can go, even a Pentium 3 2001 VAIO unable to play "Undertale."