"1990 ... In light of it's age" Age?, AGE?, AGE???? The thing's not old enough to drink beer. My father was reminiscing last night about the time he went to see Lenin speak in fomenting the Russian Revolution. And he's that's not _that_ old. 110, now you're getting old.
In any case the conceptual design started in 1969, with real design work beginning in '81. It carries multiple imaging systems, most of which have been upgraded over the years.
CCD's for imaging have been around since the early 70's.
However, space missions use only proven technology and tend to be many years behind the 'state of the art'. 1970's missions, like Voyager, used magnetic deflection vidicons and video tape recorders - the image was captured in near-real time and then sent back to earth very slowly. A very slow signal can be more easily picked from the noise of the eather, allowing the satellite to use a very low power transmitter.
By the time Hubble came around CCDs for space imaging were reasonably mature and in wide use in surveillance satellites. The Hubble has been described as a spy satellite that happens to be pointing the wrong way.
The wide-field camera of Hubble eye-candy fame is a CCD array imaging through a multitude of fine bandpass filters. The images are then 'false coloured' to translate the image for human eyesight.
Googling will reveal web sites with more Hubble information than you could ever want.