TestOut Chapters 4.5.6 & 4.5.7

System Resources

A computer assigns system resources to hardware devices, and the computer uses these assignments to communicate with the device. Three categories of system resources: •Devices use IRQ (Interrupt Request) to interact with the CPU. An IRQ allows a device to interrupt the CPU and request processing time. All new devices allow the sharing of an IRQ; older (legacy) devices had to be assigned a unique IRQ. • DMA (Direct Memory Access) channels are conduits high-speed devices use to bypass the CPU and communicate with RAM directly. ◦ Devices such as hard drives, sound cards, and FireWire cards use DMA channels to increase the speed of data transfers. ◦ Devices must have a unique DMA channel. • An I/O address (aka a port address) allows two devices in a computer to send information to each other. ◦ When a device wants to send information to another device, it addresses the data to the receiving I/O port number and sends it out on the system bus. ◦ Each device in a computer must have its own I/O address.

Self-signed Driver

A driver that includes a digital signature, but the identity of the entity that signed the driver cannot be verified. On Windows, unsigned and self-signed drivers must be manually approved.

Unsigned Driver

A driver without a digital signature. On Windows, unsigned and self-signed drivers must be manually approved. However, you cannot install unsigned drivers on x64 versions of Windows.

I/O Address

Allows two devices in a computer to send information to each other. Each device in a computer must have its own I/O address.

Hot Swapping/Plugging

Are devices that can be added and removed without shutting down the computer (technically speaking, hot plug refers to automatically detecting and configuring devices that are added, while hot swap refers to the ability to both add and remove devices). • Hot swapping must be supported by the BIOS, the bus type or controller, the device, and the driver/operating system. • USB and FireWire are examples of buses and devices designed specifically with hot swap support. • Most newer SATA drives are hot swappable. • When you connect a hot swappable device, Windows automatically detects the device, configures a driver (if one is already installed), and enables the device. • To remove a hot swappable component, use the Safely Remove Hardware feature to shut down the device before unplugging it from the system.

Signed Drivers

Are drivers that include a digital signature. The digital signature proves that the driver: • Comes from the reported publisher. • Has not been altered or modified • Is compatible with the operating system version.

DMA (Direct Memory Access)

Conduits used by high-speed devices to bypass the CPU and communicate directly with RAM.

What is the difference between hot swappable devices and plug-and-play devices?

Hot Swappable: You can insert or remove device without rebooting the computer. Plug-and-Play: Automatically detected by the system and the driver is automatically loaded.

Driver

Is a program that enables the operating system to interact with hardware devices. • Both legacy and plug and play devices need drivers to configure and use the device. • Windows detects newly installed devices and tries to find and load the driver automatically. ◦ If Windows cannot find a suitable driver, you are prompted to identify alternate locations to search in order to find the correct driver.

What should you do before installing a device?

Obtain the latest driver

Device Manager: What does an icon with a black down-arrow mean?

The device is disabled.

Device Manager: What does an icon with a yellow exclamation mark mean?

The device was detected, but could not be configured properly. In this case, make sure you have the latest driver for the device.

IRQ (Interrupt Request)

The method used by different system devices to interact with the CPU. It allows a device to interrupt the CPU and request processing time.

What is the purpose of the following?: On the file menu in Device Manager, select View > Resources by type (or Resources by connection).

To view all resources used by the computer. An example to use this would be to view a list of all IRQs and the device using each IRQ.

Device Manager: If the icon for the device is not there, then Windows did not detect the device. What should you do next?

Try scanning for new hardware or rebooting the system to detect the device.

For internal and non-hot swappable devices, what should you do before installing the device?

Turn off and unplug the system

For which type of device will you typically install the driver before you connect the device to your system?

USB devices

Plug and Play

Used by newer systems to automatically configure the resources each device needs. • The device, the BIOS, and the operating system must support plug and play standards. • All new devices and operating systems are plug and play compatible. • Plug and play allows IRQ sharing and ensures that the DMA and I/O resources used by each device are unique. • A legacy device is one that does not support plug and play. In older systems, you had to manually configure the resources used by each device. • Although a plug and play system attempts to assign configuration resources around a legacy device's needs, legacy devices often interfere with a plug and play system's ability to properly assign resources.

What should you do before purchasing a device?

Verify that it is compatible with the version of Windows you are running.

Device Manager

View installed devices and their status, update drivers, disable devices, and uninstall devices.

Which of the following are three types of system resources that are USUALLY automatically assigned? a) Device drivers, IRQ, interrupt address b) Digital signature, DMA channel, driver updates c) Power, I/O address, IRQ d) I/O address, IRQ, DMA channel

d) I/O address, IRQ, DMA channel