Abstract: A PC-based diagnostic system is modular-based, and includes a motherboard, a backplane board, a PCMCIA board, and a keypad adapter board. The motherboard communicates with I/O modules connected to the backplane board, PCMCIA modules connected to the PCMCIA board, and with a keypad or a mouse through the keypad adapter board. Based on the type of device to be tested, various diagnostic programs can be accessed internally to provide the signals used to perform the test. A system controller and a processor are provided on the motherboard to control the transfer of data and control from the motherboard, through the backplane, and to the I/O modules. Additional select lines are provided to select one or more I/O modules during a test. An ISA bus is also provided in a standard arrangement.

Abstract: A method and apparatus for measuring the concentration of one or more emission gases in the exhaust of a vehicle, including a conventional gas analyzer and a transducer for monitoring at least one parameter directly related to the operating condition of the vehicle. Samples of gas emissions are supplied to the gas analyzer and the transducer is monitored while the vehicle is operated in a convention manner. A running history of readings of exhaust gas concentration(s) of interest is maintained during vehicle operation with earlier readings being supplanted by recent ones. Upon the occurrence of a predetermined event, the running history is preserved in order to provide a correlation between the exhaust gas concentrations and known operating parameters of the vehicle.