The move from manuscript to print reshaped the alphabet, because a printer must decide once and for all what the letters look like and how many there are, where a scribe can improvise.
Printing in Church Slavonic began outside the Slavonic Orthodox lands. Schweipolt Fiol, a printer working in Krakow, produced liturgical books in Cyrillic type in 1491, and they are the earliest printed Slavonic books known. Later, Francysk Skaryna printed a series of biblical books in Prague and then in Vilnius, in a Slavonic shaped by his own east Slavic speech, in the second and third decades of the sixteenth century.
Printing in Moscow began later and more painfully. The Apostol produced by Ivan Fyodorov in 1564 is the first dated Moscow imprint, and Fyodorov subsequently left the city and continued his work further west.
Three consequences followed for the letters. The type was cut on the model of the half ustav hand, so the printed alphabet preserves a fourteenth century compromise rather than the eleventh century book letter. The repertoire was fixed, including the superscripts, the accents and the several forms of o, which made the orthography of the printed books more uniform than any scriptorium had achieved. And the church books and the secular books began to diverge, a divergence that became a formal split when a separate civil type was cut in the early eighteenth century.