user: Question: What is the cpu of the calculator released in 1993?
Columns: ['Calculator', 'CPU', 'RAM', 'Display Size', 'Programming Languages', 'Link Abilities', 'Year Released', 'Predecessors', 'Successors']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['TI-73/TI-73 Explorer', 'Zilog Z80 @ 6 MHz', '25 KB of RAM, 512KB of Flash ROM', '96×64 pixels 16×8 characters', 'TI-BASIC , Assembly (via Mallard), Flash Apps', 'I/O Port', '1998/2003', 'TI-80', 'None']
SQL:

assistant: SELECT "CPU" FROM "Table" WHERE "Year Released" = '1993';