An FIR filter and setting method of filter coefficients thereof enabling the prevention of breakdown of equi-ripple of weighted approximation error and preservation of gain of the pass band into approximately constant. When the keypad is linked to a computer, the keypad can be used to enter operation commands to the computer to perform processes desired, also can be switched to calculator function to perform numeric calculation when a switch button key on the keypad is depressed. According to the method, leased line data can be transparently transmitted by adding minimum function blocks to the DSL modem, and with the simple circuit structure, the blocks can be integrated into one chip such that no additional external circuits are needed and a low-priced DSL modem chip that can transmit leased line data can be implemented. Moreover, through appropriate selection of attribute operations, and coding of such operations using directly executable program code, optimal query engine performance may also be obtained. In an embodiment, the shell is made of a vacuum-formed acrylic sheet that is formed, plumbed, andor fiberglassed according to specific methodologies. The delay element delays signals passing through the signal lines so as to make the delays of the signals substantially equal to each other, compensating for the signal delay time generated by the line length difference.