<National Semiconductor logo>-829
data book with lots of tech info
This chip, the MM5777 and the MM5737 are very similar.
This chip is basically an MM5737 without the LED segment drivers, but with red and green LED drivers. The keyboard is connected so that the equals sign is paralleled with the minus sign, and the test button replaces the equals sign. That way, when you enter an equation like "3+4=7 test", you are actually entering "3+4-7=" If your answer is correct, the result is 0, and the green LED is lit. Otherwise the red LED is lit.