Chwarter I Un or 12:45 was a Welsh-language group, which was originally formed for the Inter-College Eisteddfod in Bangor in 1979. Competing under name MAC, they won the best rock song competition with "KO yn y Fro".
During the inaugural Sgrech magazine Awards Night Chwarter I Un won the prize for "The 1979 Most Promising Group". Gradually, over the years there has been considerable change in style and membership.
The original members were Tim Hartley - Vocals, Gwyn 'Scrots' Elfyn - Vocals, Gron Edwards - Lead Guitar, Dafydd Rhys- Guitar, Trumpet, Dominic Griffiths - Bass, Geraint 'Tonto' Jones - Drums. Owen Owens and Rhys Powys also drummed for the band in college.