2.1 Laptops and Portable Devices Part 4

Posted April 19th, 2007 by admin

A+ Essentials Study Guide Laptops - Part 4

2.1 Identify the fundamental principles of using laptops and portable devices Part 4

> LCD technologies (e.g. active and passive matrix, resolution such as XGA, SXGA+, UXGA, WUXGA, contrast ratio, native resolution)

A graphics processing unit (GPU) is a microprocessor that handles the calculations necessary for 3-D graphics rendering. Like a CPU, a GPU produces a lot of heat. Most laptops have graphics capability built into the motherboard or have smaller graphics cards with a GPU designed specifically for laptop use. GPU manufacturers ATI and nVidia both make GPUs specifically for laptops. Laptops frequently share memory between the CPU and the GPU, saving space and reducing power consumption.

Active and Passive Matrix

Active: A liquid crystal display (LCD) made from an array of liquid crystal cells using active-matrix technology. Also known as a “TFT display,” in its simplest form there is one thin film transistor (TFT) for each cell. This type of display works well with notebook computers because of its shallow depth and high-quality color. Active-matrix displays are viewable from wider angles than most passive-matrix displays.

An active matrix display uses one transistor per crystal cell.
Viewable from wider angles than most passive-matrix displays
Better quality than passive matrix.

Passive: A common LCD technology used in earlier laptops and small readouts. Passive matrix displays are not quite as sharp and do not have as broad a viewing angle as active matrix (TFT) displays, but they have improved dramatically over the years.

Looking head on into a passive matrix screen is not all that different than looking at an active matrix (TFT) screen. The difference is more noticeable with the viewing angle. A person looking from the side sees a dimmer image with passive matrix.

A passive matrix display uses a transistor for each row and column of crystal cells.
Not as good quality as active matrix.
Less expensive than active matrix.
A dual scan display is a type of passive matrix display used on lower cost notebooks.

Resolution

XGA: (eXtended Graphics Array) XGA supports a resolution of 1024 x 768 pixels with a palette of 256 colours, or 640 x 480 with high colour (16 bits per pixel). XGA-2 added 1024 x 768 support for high colour and higher refresh rates, improved performance, and supports 1360 x 1024 in 16 colours.

SXGA+: (Super eXtended Graphics Array) Is commonly used on 14 inch or 15 inch laptop LCD screens with a resolution of 1400 × 1050 pixels. SXGA+ is also the maximum resolution native to many high-end video projectors.

UXGA: (Ultra eXtended Graphics Array) A standard monitor resolution of 1600 × 1200 pixels.

WUXGA: Stands for Widescreen Ultra eXtended Graphics Array and is a display resolution of 1920×1200 pixels with a 16:10 screen aspect ratio. It is a wide version of UXGA, and is appropriate for viewing North American HDTV, which uses a 1920×1080 image at a 16:9 ratio.

The 16:10 aspect ratio (as opposed to the 16:9 used in widescreen televisions) was chosen because this aspect ratio is appropriate for displaying two full pages of text side by side. It also allows viewing of 16:9 video on a computer with player controls visible.

> Input devices

Function (Fn) keys: Fn is a modifier key on PC keyboards used in a compact layout to combine keys which are usually kept separate. It is typically found on laptops, since a full sized keyboard would be difficult to fit in a laptop chassis. It is also found in many full-sized 'multimedia' and 'office' keyboards, named F Lock key.

Unlike other modifier keys such as Shift , the control processor inside the keyboard typically sends out a different keycode depending on whether the Fn key is depressed. This allows the keyboard to emulate a full sized keyboard.

In addition to being mapped to standard keyboard keys like Scroll Lock and Num Lock, the Fn key combinations may also be mapped to control system interfaces to change the LCD brightness, VGA output, or speaker volume on most laptop computers.

Touchpad: Is an input device commonly used in laptop computers. They are used to move the cursor, using motions of the user's finger. They are a substitute for a computer mouse, some touchpads can emulate multiple mouse buttons by either tapping in a special corner of the pad, or by tapping with two or more fingers. Touchpads vary in size but are rarely made larger than 20 square centimeters (about 3 square inches).

Touchpad and a Pointing stick

Pointing Stick: (trademarked by IBM as the TrackPoint) is used to control the position of the cursor on the screen. The pointing stick is usually a rubber dot that is located between the G, H and B keys on the laptop keyboard. To navigate the cursor, pressure is applied in the direction intended to move.

> Identify and distinguish between mobile and desktop motherboards and processors including throttling, power management and WiFi

Motherboards

While most desktop computers use either ATX or microATX motherboard form factors, laptop (notebook) computers generally use highly integrated, customized and miniaturized motherboards designed by the manufacturers. This is one of the reasons that notebook computers are difficult to upgrade and expensive to repair, just the failure of one integrated component requires the replacement of the entire motherboard, which is also more expensive than a regular motherboard due to the large number of integrated components in it.

Proccessors

The objective of a notebook computer is to provide the performance and functionality of a desktop computer in a portable size and weight. Low power consumption is a primary consideration in the choice of a notebook processor. Thus one of the main characteristics differentiating mobile processors from desktop CPUs is thier lower power consumption.

Mobile CPU Characteristics

Runs at a lower voltage and clock speed.

Advantage: reduces heat and power consumption.

Disadvantage: slows the processor down

Laptop processors typically use a surface-mount or slot-mount form factor (some use a Micro-FCBGA (Flip Chip Ball Grid Array), which uses balls instead of pins.) while desktop processors use a socket-mount form factor.

Advantage: saves space

Disadvantage: in some cases the processor cannot be removed from the motherboard for replacement or upgrading.

Has a sleep or slow down mode

Advantage: computer and the operating system work together to reduce the CPU speed when the computer is not in use or when the processor does not need to run as quickly.

Some laptop specific processors:

AMD

AMD Turion™ 64 X2 Dual-Core Mobile Technology
AMD Turion™ 64 Mobile Technology
Mobile AMD Sempron™

Intel

Intel® Core™2 Duo mobile processor
Intel® Core™ Duo mobile processor
Intel® Core™ Solo mobile processor
Intel® Pentium® M processor
Intel Pentium dual-core mobile processor
Intel® Celeron® M processor

CPU Throttling

Is sort of enforced power management: Even when the system is highly active, the CPU is "put to sleep" for short amounts of time. This is done when the temperature is critically high, or, by request of the user, when the system shall use less power to allow longer system usage when on battery power.

Power Management

Windows XP provides several options to manage the power consumed by a laptop. The Power Options will vary depending on the exact hardware configuration the notebook has.

To use Power Options, the computer must be Advanced Configuration and Power Interface (ACPI)-compliant, which dictates that all components are capable of power management. If one or more components are not capable of power management, you might not have ACPI functionality.

Power Options in Windows XP allow you to control the power management features of:

Display
Hard drive
Shut Down, Hibernate, and Stand by
Low battery warnings

To configure your power settings:

Click Start, click Control Panel, click Performance and Maintenance, and then click Power Options.
Or, if you see the little battery indicator on your task bar, right-click it and then click Adjust Power Properties. The Power Options Properties dialog box opens.

power settings

In the Power Options dialog box, you set options for a power scheme. Windows XP comes with several preconfigured profiles.

Most laptop manufacturers include a power management utility, and they usually offer additional power saving features beyond what is included in Windows XP.

Wifi Adapters

Wifi PCI Card