Patent ID: 7782126

Claim:
An apparatus comprising: an input; and a discriminator circuit in a first card installed a data processing system, wherein the discriminator circuit receives a low-state signal via the input, wherein the low-state signal is the result of a second card being hot-plugged into the data processing system, and wherein, upon receiving the low-state signal, the discriminator circuit: compares the low-state signal to a static signal; responsive to the low-state signal being greater than the static signal, outputs a high-voltage signal, wherein the high-voltage signal output by the discriminator circuit indicates that the low-state signal is a false low signal and wherein, responsive to receiving the high-voltage signal by an integrated circuit within the first card, the intergrated circuit ignores common critical signals received from the second card; and responsive to the low-state signal being less than or equal to the static signal, outputs a low-voltage signal, wherein the low-voltage signal output by the discriminator circuit indicates that the low-state signal is a valid low signal and wherein, responsive to receiving the low-voltage signal by the integrated circuit, the integrated circuit validly processes the common critical signals received from the second card.