Are you
ENIAC (first general-purpose computer)?
I can stand, but I don't have legs
It was a large computer consisted of multiple boxes which literally stood on the floor (ENIAC occupied a large hall) without having any legs.
I can eat without a mouth,
Card reader "ate" the punch cards to read information.
I can smell without a nose
Tube burnouts etc. was common upon operation, so I believe it actually smelt of something.
I can see without eyes
Again, card reader "saw" the information punched on the cards.
But I can't do what I'm not allowed to
Of course, like every computer, ENIAC performed only the commands which have been ordered.
Hint 1
ENIAC is now disassembled, so it's no more of it now.
Hint 2
Obviously, "ENIAC" is 5 letters long.
Hint 3
Card punch for outputting information allowed it to "speak".