Abstract: Method and apparatus for transparently executing embedded PC diagnostics from an OS-based application is disclosed. In a preferred embodiment, responsive to a user request to execute diagnostics code embedded in BIOS memory, an OS-based utility of the present invention calls an OS-independent BIOS routine for saving the state of the PC to a hard disk thereof, resetting the PC and initiating execution of the embedded diagnostics code. The embedded diagnostics code runs to completion from PC reset, saving failure and status information to a nonvolatile storage device, and resets the PC once more. The PC boots normally from reset and restores the state of the PC from the hard disk, thereby restoring the OS-based utility, which may then be used to access the saved failure and status information and display, print or otherwise act on the information.

Abstract: A method and apparatus for performing cache snoop testing on personal computers using software to initiate DMA cycles. The computer system includes an extended capabilities parallel port (ECP), which includes a 16 bit first-in first-out buffer (FIFO) that can be accessed in a test mode where software can manually write and read the FIFO. This FIFO in the ECP parallel port is used according to the present invention to implement cache snoop testing diagnostics on personal computers. In the preferred embodiment, various hardware subsystems such as system memory, the ECP port, and the DMA controller are tested first to ensure that, if a failure occurs during cache testing, the system can differentiate between cache snoop failures and other subsystem failures. Cache snoop testing according to the present invention uses the capability provided by the ECP parallel port to generate DMA cycles which transfer data from the ECP FIFO buffer into the system memory via software.