Has there been a national referendum since 1980?
Cambodia
Direct Democracyin Asia: A ReferenceGuide to the Legislation and Practice (2005), page 89 on Cambodia: There is no mechanism in for direct democracyin Cambodia. However, there had been practices of referendum: in 1945 (independence), 1955 (approving policies), 1958 (reducing number of representatives), 1959 (suspending provincial parliaments), 1960 (approving sihanouk and policies), 1961 (shorteningschool vacations), 1972 (constitutional referendum). There have been no directdemocracy practices found ever since.
Source: http://www.docstoc.com/docs/74258274/Direct-Democracy-in-Asia