Abstract: An apparatus is provided to test a device, i.e. an interface card to a computer system or an IC chip. The apparatus communicates with the computer system via a first bus and communicates with the device via a second bus. The first and second buses are standard bus such as ISA bus, EISA bus, PCI bus, and AGP bus, etc. In the apparatus, three switch circuits respectively making connection of data/address lines, power lines and a reset line of the first bus to the second bus are provided. A test program executed in the computer generates a plurality of control signal to the apparatus. A control circuit, responsive to the plurality of control signals, controls individually and selectively the turn-on of three switch circuits. By test program running in the computer system, the function test of the device can be accomplished automatically without time-consuming power-off and re-initialization of the computer system.