The present invention provides semiconductor devices capable of being
tested using one test pin and using an input/output pin without any test
pins, and methods of testing the same. One semiconductor device comprises
a test pin for inputting/outputting test data, an operation mode
controller for activating an enable signal in response to an external
reset signal and a clock signal, an operation mode storage for receiving
serial data synchronized with the clock signal through the test pin in
response to the enable signal, and an operation mode decoder for
generating operation mode selection signals in response to the serial
data stored in the operation mode storage. Another semiconductor device
comprises an input/output pin for receiving test data, a delay reset
signal generator for delaying a reset signal, a counter for counting a
clock signal in response to the reset signal to generate a counted value,
a mode register for storing the test data, and a decoder for generating
selection signals to the mode register to designate a position in the
mode register where the test data is written.