Adding adapters to the system
When adapters are added to the system, an area in memory has to be allocated to
run its programs. This can be done with either hardware switches or software
mapping.
If there is a conflict in software mapping, then the following may be true.
vThe first device to attach to an IRQ, DMA, I/O Address, or RAM location will
probably function. The second device will not be found.
vStandalone diagnostics might function properly because the device that was
found is the only device running.
Software configuration conflicts occur when the following are true.
vHardware has a different configuration than the softwarethat is using it expects.
vHardware 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.
vHardware diagnostics run error-free.
vSwapping hardware components fails to isolate the problem.
A software problemmight 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:
vKeyboard
vSerial and parallel ports
vDiskette drive
vHard disk drive
vVGA display
vClock
vMemory 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:
vIRQ level
vDMA channel
vI/O address
vROM or RAM.
Some device drivers like HIMEM.SYS are position sensitive and must be placed
before other device drivers in the CONFIG.SYS file.
Chapter9. Related Service Information 133