http://semiconductormuseum.com/MuseumLi ... olume1.pdf
Early transistor types represented the first stages of development for this new
technology, and the first devices were quite limited in performance capabilities.
Such operational characteristics as noise level, gain, operating frequency and
power handling capability were all at low levels of performance for the first
few years of transistor development, although tremendous progress was made
throughout the 1950s and 1960s.