PC Construction and Maintenance

Week 6

Peripheral Cards

Sound and Video Cards

What is a peripheral card?

• A peripheral card consists of a circuit board that slots into the computers motherboard

• Peripheral cards provide extra functionality to the computer

• Most peripheral cards conform to well known standards and should be interchangeable

• Physical compatibility of card and motherboard does not guarantee that the card will work in a particular machine

OS dependency of cards

• For a peripheral card to work on a computer, it must be recognised by the operating system

• The piece of software that controls the peripheral device is known as a driver

• The driver is critical to the behaviour of the peripheral device

• Many cards have several different drivers available, typically one driver per operating system

The device driver

• Windows and Linux systems come supplied with a wide variety of device drivers

• Although these drivers can be used with thousands of different peripheral cards, still many cards are not supported natively by the operating system

• In these cases, it is necessary to use a vendor-supplied driver

• Vendor supplied drivers are usually shipped with the card, and most manufacturers have drivers freely downloadable from their websites

Types of drivers

• For graphics cards in particular, performance is important

• New drivers come out periodically that improve performance of graphics cards

• The first set of stable and fully tested drivers released by a manufacturer are known as the “reference drivers”

Limitations of peripheral card installation

• There must be enough free resources in the system for the machine to accept a new peripheral card

• This applies more to older hardware than new hardware

• Some very new machines may not work with very old hardware

• Some very old machines may not work with some very new hardware

Hardware conflicts

• Hardware conflicts can prevent one or more peripheral cards from functioning correctly

• Conflicts occur when two cards need, or try to use the same resource

• In some cases, conflicts can be resolved by manual intervention

• In the worst case, one or other card has to be removed from the system

What are resources?

• The four main classes of resources are independent of operating system type

• They are IRQs, I/O ranges, Memory Ranges and DMA channels

• On a plug’n’play system, these resources are allocated automatically by the operating system

• Sometimes, they have to be manually configured, particularly if old hardware is being used

• Not all hardware used all four classes of resource

Resource types - IRQs• IRQs (Interrupt Requests) are needed by all peripheral

cards. On a PC, there are 16 IRQ lines, numbered 0 to 15

• When all of these have been used, devices must share IRQs

• Not all hardware supports IRQ sharing• Plug’n’Play is meant to hide this complexity from the

end user. In most cases, it works, but sometimes the system needs manual intervention

• Many IRQs cannot be used for add-on peripheral cards, as they are reserved for standard system devices

Other Resource Types

• An I/O range specifies a range of input-output ports used by the device. If the I/O range of two devices overlaps, then a hardware conflict will occur

• Luckily, most devices are not fixed to one specific range of I/O ports

• The same is true for memory-mapped ranges. A memory mapped range is just a part of the processors address space which maps to a hardware device

Resource types – DMA channels

• DMA (Direct Memory Access) channels are used by some peripheral cards

• They provide direct access between a peripheral card and the main memory without processor intervention

• A single DMA channel can typically only be used by a single device

• Most PCs support several DMA channels

The Device Manager

• To examine resources, and sort out hardware conflicts on a Windows system, use the device manager

• It is found in the control panel by clicking on the system applet in windows 95/98/ME and windows 2000

• Windows NT 4 doesn’t have an integrated device manager, instead devices are configured under separate control panel applets

Resource Management

• In the new scheme of plug and play, all resources should be automatically allocated by the operating system

• Plug’n’play helps to avoid resource conflicts• Not all older hardware is plug’n’play, and may

need to be manually configured• Even with plug’n’play hardware, the system may

not be able to resolve all conflicts if there are a large number of peripheral devices in the machine

When to use Device Manager?

• To configure device resources, when using non plug’n’play hardware

• When updating drivers to solve problems

• To check that all of the system hardware is set up correctly

• To resolve device conflicts

Sound Cards

• A computer without a sound card can only produce simple beeps from the internal speaker

• Windows will use an available sound card extensively for informative purposes

• Soundcards are needed for games and most multimedia applications

• Soundcards are both Input and Output devices• Most new soundcards are PCI cards

Type of soundcard

• Half-duplex cards can only either output sound, or input sound at a given instant, but not both at the same time

• Full-duplex cards can both input and output sound at the same time

• Full-duplex cards are typically more expensive than half-duplex

• Half-duplex cards are O.K. for general purpose windows usage, but Full-Duplex cards are recommended for communications

Properties of a soundcard

• Expect to find a game port on most soundcards• Most sound cards have the following three

external connectors, Speaker, Line in and Microphone

• Better cards have additional connectors, sometimes gold-plated

• All sound cards have internal connectors for CD-ROM drives and/or TV cards

Sound card Identification

• Creative Labs probably still the most well known producer of sound cards

• Many unbranded clones exist

• Unbranded cards can often be identified by observing number on soundcard chip

• Soundcard drivers are very specific to the type of chip on the card

Sound card installation

• Most creative labs and other well known cards will be identified by windows automatically and can use the drivers built into windows

• Many unbranded and obscure cards need a drive obtained from the vendor’s web site

• In this case, installation of the card is performed by clicking on the ‘Add new hardware’ applet in the control panel

• Half of the challenge is finding out who the manufacturer is!

Video Cards

• All systems need a graphics adapter to produce a display

• Graphics cards can vary enormously in price• Price determines speed and functionality of the

card• Good cards offload a lot of graphics processing

from the main CPU, and therefore allow a faster system

• New games require graphics cards with 3-D acceleration

Additional Features

• Some video cards additionally have an S-video or composite video outputs for connecting the computer to a TV or video

• Some cards support 3-D LCD shutter headsets for Virtual Reality and Games

• Some cards support connection to additional cards of the same model, to share the processing load and boost performance

Video RAM• The capabilities of a video card depend on several

properties of the card. • The amount of on-card video RAM determines the

maximum resolution and number of colours the card can display

• The amount of VRAM also affects performance, as new cards use VRAM as a scratch pad for the creation of objects in the image

• Analogous to the processing system, increasing VRAM increases performance of the graphics subsystem

The RAMDAC

• The RAMDAC (RAM Digital to Analogue Converter) scans the video, and converts its contents to an analogue signal in order to drive the monitor

• The speed of the RAMDAC determines the exact refresh rates and resolutions the card can do

• The RAMDAC on a typical card can run at a dozen or so specific frequencies to support different resolutions

• The faster the RAMDAC, the higher the resolution and refresh rates the card can display

The GPU

• The GPU (Graphics Processing Unit) is the main large chip on the video card

• The speed of the GPU is critical to graphics performance

• Faster GPUs give better graphics performance, but run hotter

• Some new video cards need a heatsink and fan mounted on the GPU to keep it cool

• The GPU can be overclocked with custom software to gain extra speed, but is not recommended

Typical Operating Parameters

• For small monitors 14” and 15”, a typical resolution would be 800x600 at 60Hz with as many colours as possible

• For 17” monitors, 1024x768 would allow for more desktop space

• Higher refresh rates are easier on the eyes• Non-interlaced mode is recommended to

avoid headaches

Changing the operating parameters

• Under windows, the display applet in control panel allows changing the operating parameters of the graphics adapter

• Right clicking on the desktop also allows quick access to the display applet

• If the correct driver for the card is not installed, then the settings can not always be changed above 640x480 and 16 colours

Colour Modes

• More Colours gives a better picture, but may make the computer slower, it very much depends on the type of video card being used

• In Windows terminology, High Colour is 65 thousand colours (16-bit colour), True colour is 16 million colours (24-bit colour). 256 colour mode is sometimes used on old machines, but looks very grainy

• The human eye can’t distinguish between more than 16 million colours

Installing a graphics card

• If the card is supported natively by a Windows driver, then windows should detect it at install time

• After rebooting, the display applet should allow selection of high resolution and high colour modes

• Even if the card is supported by a windows driver, it is often best to download the manufacturers own driver from the web

Installing a graphics card

• If the card is not supported by a native windows driver, then either the driver supplied on disk, or one downloaded from the web has to be used

• You can tell if windows does not recognise the card if it is listed as a “standard VGA adapter” in the control panel

• To install the card, you can click on the “Add New Hardware” applet in the control panel

Add new hardware applet

• The add new hardware applet allows manual installation of drivers for hardware that is not automatically installed by windows

• You can allow the applet to automatically detect hardware, or manually add hardware

• Sometimes manual addition of hardware is required if for some reason the auto detection fails

• If you are confident how to install a particular piece of hardware then you can skip the auto detection to save some time

Adding new hardware

• If the hardware is not supported by a native Windows driver, then you will be prompted to insert a driver disk

• Sometimes, Windows will fail to find the driver on the disk, because it is located in a folder or subfolder of the vendor supplied floppy disk or CD

• Sometimes you have to search for the driver file manually on the floppy of CD-ROM

Adding new hardware

• After the new driver has been loaded onto the hard drive, the computer will need to restart

• If the driver was the correct type for the hardware, then the device will function correctly

• If the driver was incorrect for the specific piece of hardware, then the machine may crash or hang during the boot process, or the device may simply not work properly

Safe Mode• When installing new drivers, there may sometimes be

a problem with an incorrect or out of date driver• These problems can be serious enough to lock you out

of windows• Safe mode comes in handy. It lets you boot the

operating system without loading most of the drivers• You can use same mode to remove an offending

driver and then reboot to normal windows mode• Safe mode is accessible by pressing F8 upon booting