Table schema:
CREATE TABLE table_11703336_1 (cpu VARCHAR, ram VARCHAR, display_size VARCHAR)

Question: what is the cpu for the calculator with 28 kb of ram and display size 128×64 pixels 21×8 characters?
SQL: SELECT cpu FROM table_11703336_1 WHERE ram = "28 KB of ram" AND display_size = "128×64 pixels 21×8 characters"