IBM 689912U Hardware Maintenance Manual - Page 463

Diagnostic error messages are displayed when a test program finds a problem with a hardware component. Software-generated error messages are displayed if a problem or conflict is found by an application program, the operating system, or both. For an explanation of these messages, refer to the information supplied with the installed software package. Also, refer to "Software Considerations." Multiple messages occur when the first error causes additional errors. Follow the suggested action of the first error displayed. Software Considerations Suspect a software failure if: Hardware diagnostics run error-free. Swapping hardware components fails to isolate the problem. A software problem might be the result of a mismatch between the hardware and the operating system device drivers or direct drivers. BIOS: The BIOS acts as an interface between the system hardware, application software, and the operating system. BIOS contains the instructions to operate the basic system components: Keyboard Serial and parallel ports Diskette drive Hard disk drive VGA display Clock Memory controller The BIOS then starts the IPL or Boot functions. Drivers: Device drivers are the BIOS for additional hardware. Device drivers are the communicators of the hardware assignments to the operating system, including: IRQ level DMA channel I/O address ROM or RAM Some device drivers like HIMEM.SYS are position sensitive and must be placed before other device drivers in the CONFIG.SYS file. All device drivers are not found in the CONFIG.SYS file. Advanced operating systems use .INI files to setup and start devices. Device drivers can access the hardware five ways. Reference Information 453