9 March 1980
1984 saw P.W. Botha elected to the position of President, having abolished the position of Prime Minister in 1983. These two events were preceeded by the announcement by the future president in 1980 that all South African races would take part in a constitutional conference, consisting of a trichameral parliament. Notably absent in the proposed parliament, however, was any provision for equal representation amongst members of South Africa's majority Black population, who were instead entitled to a sham form of self-governance in the homelands. 
References

Nations Online, History of South Africa (Part 2: The Republic of South Africa :: 1961–present), [online], available at www.nationsonline.org (Accessed: 12 February 2013)|

O’Malley, P. ‘1980’, from Nelson Mandela Centre of Memory, [online], available, at www.nelsonmandela.org.za (Accessed: 12 February 2013)|

South African History Online, ‘General South African History Timeline: 1980s’, [online], www.sahistory.org.za (Accessed: 13 February 2013)