When envisioning the computer on the starship Enterprise, did Gene Roddenberry not fathom computers getting more powerful even as they got smaller?

While looking in a Star Trek magazine I had, they had an explorative view of one of the Enterprise starships and the computer spanned pretty much from right behind the bridge all the way to the bottom of the saucer part, many decks in any part. I figure Roddenberry thought to have a computer that could do what the Enterprise computer can do, it had to be massive, just as you use to have to have banks of servers to some high powered computer stuff. Computers have been getting more powerful even as they are getting smaller. The tablet PCs of today I suspect has way more computing power than a desktop PC of the early 80s. With what we know today, to have a computer do what the Enterprise computer is able to do, how large or small would the computer be? If advances kept up in power vs size in the era of Starfleet, how large would they be?