Abstract: A computing apparatus, includes a first apparatus and a second apparatus, a differential transmission line that couples the first apparatus and the second apparatus to each other, a noise application unit that applies noise to the differential transmission line, a noise control unit that controls the noise application unit, and a margin measurement unit that measures an occurrence frequency of communication error between the first apparatus and the second apparatus.

Abstract: Relay buffers 600, 601, 602, and 603 in a computer module 110 and an I/O module 120 each have a noise filter circuit for determining the amplitude of a signal to/from PCIe interfaces 161 and 162 to distinguish a signal from noise and controlling ON/OFF of output signals. An I/O hub 300 and a PCIe switch 400 make a switch between enablement and disablement of the noise filter circuits in the relay buffers according to communication mode, and disables the noise filter circuits when communication is performed at a high rate. Cable removal detecting circuits 115 and 125 notify the I/O hub 300 and the PCIe switch 400 of a removal of a PCIe cable 151 to prevent a malfunction caused by noise that results from a PCI glitch.

Abstract: According to the present invention, variations in characteristic impedance and transmission loss of a signal wiring in a glass cloth wiring substrate can be reduced. There is provided a glass cloth wiring substrate in which signal wirings, plural glass cloth layers, and conductor faces are laminated, and spaces between the signal wirings, the plural glass cloth layers, and the conductor faces are impregnated with resin, wherein the glass cloth layers are formed by weaving bundles of glass fibers in a lattice shape, and the adjacent glass cloth layers are laminated on each other while rotating the warp-weft directions of the glass fibers by a predetermined angle with respect to each other. It is preferable that the rotation angle of the warp-weft directions of the glass fibers of the adjacent glass cloth layers falls within a range from 30 to 60 degrees.