Devices & Cards
Additional Boards ( Cards )
Sound Cards
1.
Video Cards
2.
Network Cards
3.
TV Tuner cards
4.
Modem Cards
5.
SCSI HDD Cards
6.
Cards for a DAS system
A new Board requires system resources to interact with the system
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I/O Addresses
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IRQ Levels
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ROM Addresses
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DMA channels
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RAM Buffers
IRQ ( Interrupt Request Line) This is the Hardware line over which a device sends a signal to get
the attention of the Microprocessor.

A separate IRQ is required for each device.

Only 16 IRQs are provided.

Only four or five - typically 5,10,11,12 & 15 are available after assignments to the KeyBoard,
Parallel port etc.

Interrupt lines , alongwith other bus lines are contained in ISA & PCI buses.
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ISA Slots. : Sometimes IRQ setting is done by jumpers & sometimes by setup program.
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PCI expansion cards are normally assigned IRQs dynamically either by BIOS or by Windows.
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In new systems ISA cards should be avoided.
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I/O Port Address : The Microprocessor communicates with a device on the port address assigned
to it.

The actual exchange of data & commands takes place through the port.

I/O port address is expressed in Hexa Decimal number.

An I/O port has a Base Address i.e. address of the first byte allocated & the contiguous address
Range.
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Each device should have different port addresses.

Many devices require multiple I/O addresses.

There are 1024 ports available.
D M A Channel : DMA channel is a route by which a device can transfer data to and from
memory without going through the processor. This transfer is coordinated by a DMA controller
chip. Eight DMA channels are supported. Bus Mastering DMA allows two devices to
communicate directly with each other.
Drivers : A driver is a piece of software that allows your computer to communicate with the
various devices attached to it. It is the middleman for communication between the Operating
system & the PC Hardware. These small programs work at very low level to integrate support for
other devices into the Operating system.
Support for any new devices can be added without interfering with the core of the O S.
Device drivers worth investigating include those for your video card, monitor, sound card,
modem, printer, network adapter, scanner, SCSI controller, tape drive, and any other drives or
cards you may have.
Most hard disks, floppy drives, CD drives, keyboards, mice, power supplies, memory, and
CPU chips don't need special drivers.
Windows 98 comes with a significant number of drivers for common devices of the PC
from different manufacturers.
Windows & Device Drivers :
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Universal Driver - Mini Driver model : For each class of Hardware such as Printers, Displays etc
windows provides a Universal Driver having capability to basically handle that device. Specific
Mini Driver may be provided by the Device Manufacturer to augment the functionality for their
device.
Virtual Device Drivers : The Universal Drivers provided by Windows is called Virtual Device
Driver. Multiple devices can use these drivers simultaneously. They have an extension of VXD.
In the device driver's name, X' is replaced by letter indicating the device such as 'P' for printers
.VPD, that of display - VDD & so on. Windows 98 provides hundreds of VXDs for specific
devices so that a DOS driver may not be used by loading with Autoexec.bat and config.sys.
PLUG and PLAY (PnP):
With Plug and Play feature, you can attach a peripheral device to your PC, turn it ON and the
device is automatically configured and starts working. This implies that 1.
The device is detected and recognized.
2.
The device's resource configuration (i.e. IRQ, I/O address) is set up correctly without any
conflict with other devices.
3.
An appropriate driver is assigned to the device.
For Plug & Play to work properly, your PC should have 1.
A Plug and Play (PnP) Bios. This is usually a Flash memory because here the system
configuration information is kept.
2.
The OS should be Windows 98 or later.
3.
The device i. e. the add on card should be PnP compliant.
Plug and Play feature would not handle & configure non- PnP or 'Legacy' devices. But Windows
98 like PNP OS can detect these devices. You can also reserve resources for them.
PnP-compliant devices must have the following characteristics:
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
The device must have a "signature" that it communicates to the PC when it is queried by the PC.
Windows then looks up this signature in its driver database. If a compatible driver is found, driver
will be loaded for that device.

All configurable resources of the device must be software-adjustable; that is, it is not necessary to
physically set jumpers or switches on the hardware to reconfigure it. ( OR a combination of
jumper setting & software setting is also OK)

The driver, if supplied, must be capable of instructing Windows which resources the device can
occupy, and must be able to receive instructions from Windows and reconfigure the card
accordingly so that Windows can read all the possible configurations from all the drivers, and then
reconfigure each one so that there are no conflicts.
Expansion Buses and Plug and Play : PnP relies to a great extent on the PCI bus. The PCI
devices are 'self aware' i.e. they know the resources they need. There is also a ISA cards' PnP
specification. However ISA cards are not as suitable as the PCI cards for PnP function.
How Windows handles Plug & Play :
PnP Bios : When PC is started, the ROM BIOS performs Power On Self Test to check
hardware. A PnP Bios enumerates and tests all the PnP compliant devices on the system. The Bios
routines gather the resource configuration of the devices and then resolves any resource conflicts.
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MotherBoards & BIOSes after 1995 are usually PNP complient
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The cards are configured everytime you boot the system by the configuration Manager in the
BIOS.
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Also, when a new Board is installed, it may result in moving around of all the other Board's
resources to different settings.

There is a setting in BIOS of "Whether the OS is PNP". The setting should be NO so that the
Configuration Manager built into the BIOS handles assignments of system resources.
If Bios is Non-PnP Windows enumerates the devices directly. And stores everything in the
Registry. This task is performed by the virtual device driver called Configuration Manager.
The PnP devices will be configured every time you boot the PC
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Installing PnP Boards ( Cards or add-in devices )
1.
Insert the device in your PC and put it ON.
2.
Windows will detect and configure it. If it cannot find a driver, it will prompt for a driver.
3.
If the device fails to work at first instance, boot the system again two or three times. This will
give a chance to the configuration manager to reshuffle the resources and resolve conflicts.
Managing Interrupts :

Interrupt Request Lines 00,01,02,08 are not present in any slot & hence not available. IRQ 2 is
cascade IRQ. It is connected to IRQ 9 of the second Interrupt controller. Prioritywise the Interrupts
are : 00,01,02,08 ----- 15, 3 -----7.

PCI slots use level sensitive interrupts. Each PCI slot can access four interrupts. INT#1 to
INT#4. INT - IRQ settings are to be kept normally on AUTO in BIOS. However, a PCI slot INT #
( e.g. a slot no 3 having a sound card ) can be mapped to a particular IRQ say IRQ 5 for that cards
requirement.

PCI cards are assigned IRQs dynamically either by the BIOS or by Windows.
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PCI Bus IRQ steering : This function allows Windows to allocate IRQs to PCI devices.
Previously the BIOS assigned IRQs to PCI devices. When PCI steering is enabled ( the default),
Windows overrides the BIOS assignments. This is useful when ISA cards are also used in the
system. Instead of manually resolving the IRQ settings ( Because non PNP ISA cards will not be
automatically assigned IRQ ), Windows re-arranges the IRQs after considering the ISA card
requirement automatically. It reserves the particular IRQ for PCI cards which is then declared as
'IRQ holder for PCI steering'. This can be viewed in Device Manager by double clicking on
Computer Icon to view IRQ settings. Some IRQs are listed there as "'IRQ holder for PCI steering".
PCI steering setup is found by displaying properties of PCI BUS in the System Devices node of
Device Manager. Select or deselect the options given in the IRQ steering page and try again by
restarting the PC when there is problem of cards setup.

ISA cards : These are now finally being phased out. As far as possible do not use ISA cards.

ISA cards have edge sensitive interrupts hence ISA devices cannot share interrupts.
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
IRQs can be reserved for ISA devices in CMOS setup of PCI/PNP configuration. Here, some
interrupts can be defined as reserved for ISA slots only.
DEVICE MANAGER
Normally, PCI cards will be configured automatically. These settings & other device details will
be found in Device Manager. For Device Manager : Right Click on MYConputer  Properties 
Device Manager Tab OR Control Panel  System ( Double Clk on System icon )
You can view devices by TYPE or CONNECTION :
If you display the hardware devices by type, a device will be listed under its hardware category.
E.g. CD ROM Network Adapter, KeyBoard etc.
If you display the hardware devices by connection, a device will be listed under the hardware it is
connected to. For example, if PCI bus is listed, the various devices attached to the PCI Bus will be
listed beneath it.
You can also display the Hardware Resource wise i.e. Interrupt/ IO / DMA etc. For this, double
click the Computer node in Device Manager. There is also another tab for reserving Resources. If
a legacy device is demanding a fixed resource, you can reserve that resource here so that it will not
be automatically assigned to other PCI devices.
Device Properties :
Select the device in Device Manager & click on Properties Button. In the Device's Properties Sheet
you can -- 1. Adjust the Resource settings 2. Change the Device Driver
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