@Mammmood - The term VDT is not one that I hear often nowadays. I only hear it in situations where there are “dummy” terminals.
I used to work at a company that had a bunch of computer terminals. Each computer was a VDT workstation. They all performed the same function, which was to run a simple data entry program.
They were hooked up to a mainframe, which was the real brain of the operation. I don’t know that the computers had their own brains – or chips – so to speak. I don’t know exactly how that works, but at best, they were stripped down versions of real computers.