Transfer of physical shares from my grandfather to mine and have in demat

My grandfather is holding IPO released physical share certificates for more than 25 years.

I want to transfer them to my name and hold it in demat form.

How can I go about doing it?

you have to do Dematerialization those shares, for that you have to open a demat account and Fill up a dematerialization request form, which is available with your DP. Submit your share certificates along with the form; and you will Receive credit for the dematerialized shares into your account