A new apparatus for reading keyboard-commands of a portable computer comprises a shift register, a keyboard-matrix circuit, a filter, a buffer, an address generator, a mapping device, a comparator, and an output device. The shift register is for outputting a plurality of scan-input signals and a reference signal. The keyboard-matrix circuit is for outputting a scan-output signal according to the scan-input signals. The keyboard-matrix circuit includes a plurality of nodes corresponded to the keyboard buttons, respectively. The filter is for filtering the noise of the scan-output signal. The buffer is for further stabilizing the filter signal. The address generator is for reading the location of the node corresponding to the button being pressed. The mapping device is for outputting a mapping signal corresponding to the button being pressed. The comparator is for outputting a comparing signal, which represents the command corresponded to the pressed button. The output device is for outputting a data clock signal and a data output signal serially according to the comparing signal.