Complex sentence: It needed to be this large due to the number of features included--the most available at the time--manufacturing technology did not allow for a cost feasible implementation integrating all of the functions into a smaller number of chips.
Split into simpler sentences: It needed to be this large because of the number of features included (the most available at the time). At the time, manufacturing technology was incapable of integrating all of the functions into a smaller number of chips.