In 1955 Armando received Bachelor of Arts at the University of Rome.
Armando started his career in Rome, where he was an archivist of state and then conservator of the manuscripts in Accademia dei Lincei until 1972. After that he held the position of professor of Palaeography and diplomacy in such Universities as University of Salerno and University of Rome. Since 1991 Armando serves as a professor of Latin Palaeography at Scuola Normale Superiore in Pisa, Toscana, Italy.
He taught at several prestigious foreign universities, such as Michigan University in Ann Arbor, Stanford University, Berkeley University, Collège de France, École des Hautes Études en Sciences Sociales, and directed two major scientific journals, 'Writing and Civilization', founded by him in 1977, and 'Alfabetismo and written culture.'
On June 14, 1958 Armando married a historian Franca Nardelli.