Cadmean Alphabet

founder of Thebes
inventor of 16 letters of greek
700-403 bc] Pelasgian characters used for Greek, and usually called Cadmean.  Diodorus Siculus told us that Orpheus used the Pelasgian alphabet, which originally consisted of 13 consonants, and presumably additional letters for vowels.[12]  In the time of Diodorus, there was some confusion as to whether the number of letters should properly be 12 consonants, or 13 consonants, and the controversy apparently focused upon the Pelasgian letter Ng.  The Cadmeans abandoned Ng as an independent letter, and replaced it with other conventions, such as the medial -gg-.[13]  Cadmus increased the count by 3 letters, making a Pelasgian alphabet of 16 consonants.  Cf. Cadmean alphabet [403 bc].
alphabet : [403 bc, ABC]  Cadmean characters, rearranged into the ABC order, and exhibiting the vowel order A.E.I.O.U. (=; Greek letters derived from Phoenician, sometimes called Pelasgian characters.  Cadmus is believed to have increased the letters from their original number of 13 letters to 16 letters.[19]  Cadmean script was used in Boeotian Cadmea.[20]  Epicharmus of Sicily added the 2 letters Theta and Chi (Θ, Χ).  The Dionysian devotee Simonides purportedly modified the Cadmean alphabet to conform to the principles of some obscure religion,[21] and the changes of Simonides were formally adopted by the Archon Euclides in 403 bc.  Simonides devised the double-consonants Psi and Xi (Ψ, Ξ), distinguished the short Omicron (Ο) from the long Omega (Ω), and differentiated between the long Eta (Η) and short Epsilon (Ε).