You would typically go to MediaFire, use their search function, and look for "Doraemon 1979 DVD-Rip" or similar keywords.
Obtaining a complete collection of the 1979 TV series (also known as the Oyama Edition) is a significant undertaking for any fan, as the series consists of over 1,787 episodes and 30 specials aired between 1979 and 2005. Series Overview April 2, 1979.