The Squarcialupi Codex (Biblioteca Medicea Laurenziana Med. Pal. 87), an illuminated manuscript produced in Florence, Italy, is one of the few contemporary sources for the study of non-religious, i.e. "profane" music between the 13th and 14th centuries, and the largest primary source for music of the Trecento, also known as the "Italian ars nova."
"It consists of 216 parchment folios, richly illuminated and in good condition, so complete pieces of music are preserved. Included in the codex are 146 complete pieces by Francesco Landini, 37 by Bartolino da Padova, 36 by Niccolò da Perugia, 29 by Andrea da Firenze, 28 by Jacopo da Bologna, 17 by Lorenzo da Firenze, 16 by Gherardello da Firenze, 15 by Donato da Cascia, 12 pieces by Giovanni da Cascia, 6 by Vincenzo da Rimini, and smaller amounts of music by others. It contains 16 blank folios, intended for the music of Paolo da Firenze, since they are labeled as such and include his portrait; the usual presumption by scholars is that Paolo's music was not ready at the time the manuscript was compiled, since he was away from Florence until 1409. There is also a section marked out for Giovanni Mazzuoli which contains no music.
"The manuscript was almost certainly compiled in Florence at the monastery of Santa Maria degli Angeli, probably around 1410–1415. Paolo da Firenze may have had some part in supervising the effort, though it cannot be proven, and the omission of his music has been a puzzle for musicologists. The manuscript was owned by renowned organist Antonio Squarcialupi in the middle of the 15th century, then by his nephew, and then passed into the estate of Giuliano di Lorenzo de' Medici, who gave it to the Biblioteca Palatina in the early 16th century. At the end of the 18th century it passed into the ownership of the Biblioteca Medicea Laurenziana.
"The first folio in the codex states: "This book is owned by Antonio di Bartolomeo Squarcialupi, organist of Santa Maria del Fiore." Illumination is done in gold, red, blue and purple.
"All of the compositions in the codex are secular songs: ballata, madrigals, and cacce: there are 353 in all, and they can be dated to the period from 1340 to 1415. The other substantial collection of music from the period, the Rossi Codex (compiled between 1350 and 1370), contains some earlier music" (Wikipedia article on Squarcialupi Codex).