Portable System Design Elements
Portable systems are designed to be smaller and lighter than desktops, and much of the development work that has been done on desktop components has certainly contributed to this end. Much of this development has been in simple miniaturization. For example, whereas 3.5-inch hard drives may be popular on desktops, most laptops would not have room for these devices. Instead, they normally use 2.5-inch hard drives, which are a direct result of the miniaturization that has occurred in hard-drive technology over the past few years. Some of the subnotebook and Tablet PC systems use even smaller 1.8-inch drives first made popular in portable music players.
In addition to miniaturization, however, advancements in three other areas have contributed greatly to the design of today's laptop computers: flat-panel displays, power systems, and thermal management.
Flat-Panel Displays
The sleek lines of flat-panel Liquid Crystal displays (LCDs) have caused them to be seen increasingly more often on desktops. It was not long ago, however, that these displays were almost exclusively in the domain of laptops.
A flat-panel display is one of the most visually apparent components of a laptop. They are also usually the component that has the greatest impact on the size, shape, and cost of a laptop. In the early days of portables, the only affordable portable display was the small CRT monitor, a device that was so power-hungry that it required AC power. These displays were also bulky, causing early portables to look like small suitcases. When gas-plasma displays became available, the size of portables diminished to that of a lunchbox or briefcase. Still, the power requirements of gas-plasma displays again mandated a nearby AC outlet. It was not until the development of large, low-power LCDs that the familiar clamshell-style, battery-powered laptop became a reality.
As the internal components of a laptop became increasingly small, the laptops gradually shrunk in size to the point where they were no larger than a paper notebook. Indeed, the category of notebook computers originally started out with a footprint no larger than 8.5x11 inches. In the past few years, however, as high-quality LCD screens became available in larger and larger sizes, the size of some notebooks also increased.
Low Power Consumption
Like the car that spends most of its time in a garage, or the pleasure boat that spends most of its time at the dock, portable computers spend most of their time in a decidedly non-mobile environmenton a desk connected to an AC power outlet. Take away a laptop's battery, however, and you have greatly diminished its value. In fact, one of the primary features of importance to a laptop buyer is the "battery life"the length of time the system can run on a single battery charge.
Environmental concerns are leading to the development of more efficient power-management technologies, but, obviously, operating a computer from a battery imposes system limitations that designers of desktop systems never had to consider before the advent of battery-powered portable systems. What's more, the demand for additional features, such as DVD and CD-RW drives, larger displays, and ever faster processors, has enormously increased the power drain on the typical system. The problem of conserving power and increasing the system's battery life is typically addressed in three ways:
· Low-power components Nearly all the components in today's portable systems, from CPUs to memory to displays and drives, are specifically designed to use less power than their desktop counterparts.
· Increased battery efficiency Newer battery technologies, such as lithium ion and lithium polymer, are enabling batteries and power supplies to be lighter and have greater capacities, allowing for longer battery life on a single charge.
· Power management Operating systems and utilities that turn off specific system components, such as disk drives, when they are not in use can greatly increase battery life.
Thermal Management
Perhaps a more serious problem than battery life in portable systems is heat. All electrical components generate heat, of course, and in the confines of a laptop this heat can be a significant problem. Inside a laptop, a large number of components are packed in a relatively small space, creating an extremely high concentration of thermal energy. This energy must somehow be dissipated. In most desktop systems, this is accomplished by using fans that continuously ventilate the empty spaces inside the system. Because fans use up battery power, however, portable systems must be designed to run fan-free most of the time and therefore employ innovative systems for moving and dissipating heat.
The worst culprit, as far as heat is concerned, is the system processor. When they were first released, the amount of heat generated by Intel's 486 and Pentium processors became a problem even in desktop systems. Newer and faster processors consume more and more power. It became clear to processor manufacturers such as Intel and AMD that special processor designs would be necessary to reduce power consumption and thermal output in mobile systems. Modern mobile processors benefit from technology featuring lower voltages, smaller die sizes, larger integrated caches, and, in general, lower power consumption than their predecessors.
Because many portable systems are now being designed as replacements for desktops, they require the most powerful processors available. Even the newest and fastest processors designed for desktop systems are often adapted for use in mobile systems. Even with dedicated designs for mobile systems, these high-speed processors can generate surprisingly large quantities of heat.
To address this problem, Intel and AMD have created special methods for packaging mobile processors that are designed to keep heat output to a minimum. Mobile processors also reduce heat through the use of extra-low-voltage designs (multiple voltages in recent designs) and by integrating both the Level 1 and Level 2 memory cache directly on the processor die. These techniques, by the way, not only reduce heat but also lower power demands and thus increase battery endurance.
However, even the best mobile processor designs will still result in a substantial quantity of heat being generated in a small space. Usually this heat is more concentrated than that inside a desktop. To cope with this problem, many notebook components are designed not only to require little space and power but also to be able to withstand high temperatures.
Portable systems are designed to be smaller and lighter than desktops, and much of the development work that has been done on desktop components has certainly contributed to this end. Much of this development has been in simple miniaturization. For example, whereas 3.5-inch hard drives may be popular on desktops, most laptops would not have room for these devices. Instead, they normally use 2.5-inch hard drives, which are a direct result of the miniaturization that has occurred in hard-drive technology over the past few years. Some of the subnotebook and Tablet PC systems use even smaller 1.8-inch drives first made popular in portable music players.
In addition to miniaturization, however, advancements in three other areas have contributed greatly to the design of today's laptop computers: flat-panel displays, power systems, and thermal management.
Flat-Panel Displays
The sleek lines of flat-panel Liquid Crystal displays (LCDs) have caused them to be seen increasingly more often on desktops. It was not long ago, however, that these displays were almost exclusively in the domain of laptops.
A flat-panel display is one of the most visually apparent components of a laptop. They are also usually the component that has the greatest impact on the size, shape, and cost of a laptop. In the early days of portables, the only affordable portable display was the small CRT monitor, a device that was so power-hungry that it required AC power. These displays were also bulky, causing early portables to look like small suitcases. When gas-plasma displays became available, the size of portables diminished to that of a lunchbox or briefcase. Still, the power requirements of gas-plasma displays again mandated a nearby AC outlet. It was not until the development of large, low-power LCDs that the familiar clamshell-style, battery-powered laptop became a reality.
As the internal components of a laptop became increasingly small, the laptops gradually shrunk in size to the point where they were no larger than a paper notebook. Indeed, the category of notebook computers originally started out with a footprint no larger than 8.5x11 inches. In the past few years, however, as high-quality LCD screens became available in larger and larger sizes, the size of some notebooks also increased.
Low Power Consumption
Like the car that spends most of its time in a garage, or the pleasure boat that spends most of its time at the dock, portable computers spend most of their time in a decidedly non-mobile environmenton a desk connected to an AC power outlet. Take away a laptop's battery, however, and you have greatly diminished its value. In fact, one of the primary features of importance to a laptop buyer is the "battery life"the length of time the system can run on a single battery charge.
Environmental concerns are leading to the development of more efficient power-management technologies, but, obviously, operating a computer from a battery imposes system limitations that designers of desktop systems never had to consider before the advent of battery-powered portable systems. What's more, the demand for additional features, such as DVD and CD-RW drives, larger displays, and ever faster processors, has enormously increased the power drain on the typical system. The problem of conserving power and increasing the system's battery life is typically addressed in three ways:
· Low-power components Nearly all the components in today's portable systems, from CPUs to memory to displays and drives, are specifically designed to use less power than their desktop counterparts.
· Increased battery efficiency Newer battery technologies, such as lithium ion and lithium polymer, are enabling batteries and power supplies to be lighter and have greater capacities, allowing for longer battery life on a single charge.
· Power management Operating systems and utilities that turn off specific system components, such as disk drives, when they are not in use can greatly increase battery life.
Thermal Management
Perhaps a more serious problem than battery life in portable systems is heat. All electrical components generate heat, of course, and in the confines of a laptop this heat can be a significant problem. Inside a laptop, a large number of components are packed in a relatively small space, creating an extremely high concentration of thermal energy. This energy must somehow be dissipated. In most desktop systems, this is accomplished by using fans that continuously ventilate the empty spaces inside the system. Because fans use up battery power, however, portable systems must be designed to run fan-free most of the time and therefore employ innovative systems for moving and dissipating heat.
The worst culprit, as far as heat is concerned, is the system processor. When they were first released, the amount of heat generated by Intel's 486 and Pentium processors became a problem even in desktop systems. Newer and faster processors consume more and more power. It became clear to processor manufacturers such as Intel and AMD that special processor designs would be necessary to reduce power consumption and thermal output in mobile systems. Modern mobile processors benefit from technology featuring lower voltages, smaller die sizes, larger integrated caches, and, in general, lower power consumption than their predecessors.
Because many portable systems are now being designed as replacements for desktops, they require the most powerful processors available. Even the newest and fastest processors designed for desktop systems are often adapted for use in mobile systems. Even with dedicated designs for mobile systems, these high-speed processors can generate surprisingly large quantities of heat.
To address this problem, Intel and AMD have created special methods for packaging mobile processors that are designed to keep heat output to a minimum. Mobile processors also reduce heat through the use of extra-low-voltage designs (multiple voltages in recent designs) and by integrating both the Level 1 and Level 2 memory cache directly on the processor die. These techniques, by the way, not only reduce heat but also lower power demands and thus increase battery endurance.
However, even the best mobile processor designs will still result in a substantial quantity of heat being generated in a small space. Usually this heat is more concentrated than that inside a desktop. To cope with this problem, many notebook components are designed not only to require little space and power but also to be able to withstand high temperatures.
No comments:
Post a Comment