user: Question: With April 1986 as the introduced, what is the least clock speed (MHz)?
Columns: ['Processor', 'Model', 'Clock speed (MHz)', 'L1 cache (bytes)', 'Introduced', 'Discontinued']
Types: ['text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['MC68000', 'Lisa', 5.0, '—', 'January 1983', 'January 1984']
SQL:

assistant: SELECT MIN("Clock speed (MHz)") FROM "Table" WHERE "Introduced" = 'April 1986';