Software Considerations; Bios; Drivers - IBM 2179 Hardware Maintenance Manual

v Standalone diagnostics might function properly because the device that was
found is the only device running.
Software configuration conflicts occur when the following are true.
v Hardware has a different configuration than the software that is using it expects.
v Hardware memory address space is in conflict with memory used by the
application software.

Software considerations

Suspect a software failure if one of the following is true.
v Hardware diagnostics run error-free.
v 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.
The BIOS contains the instructions to operate the basic system components:
v Keyboard
v Serial and parallel ports
v Diskette drive
v Hard disk drive
v VGA display
v Clock
v Memory controller.
The BIOS then starts the IPL or Boot functions.

Drivers

Device drivers are the BIOS for additional hardware. They are the communicators
of the hardware assignments to the operating system, including the following:
v IRQ level
v DMA channel
v I/O address
v 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.
Not all device drivers are found in the CONFIG.SYS file. Advanced operating
systems use .INI files to set up and start devices.
Device drivers can access the hardware in five ways.
v Operating system direct to hardware using a direct driver
Direct drivers, which bypass BIOS, have the advantage of faster throughput, but
the disadvantage of limited error-handling capability and reduced software and
hardware compatibility and flexibility. This method is not used in the IBM PC
Series systems.
Chapter 8. Related service information
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