What can a laptop do?

Answer 1

In a way, the skyrocketing popularity of laptop computers is ironic. They're completely portable, and they use less power and make less noise than desktop models. But, they're often a little slower and have less graphics and sound processing power, although these differences can be too small for most users to notice.

Laptops are also more expensive than desktops. The price gap is closing, though -- laptop prices are falling faster than desktop prices, and laptop PCs actually outsold desktop models for the first time in May of 2005

Overall, laptop and desktop computers are very similar. They have the same basic hardware, software and operating systems. The primary difference is how their components fit together.

A desktop computer includes a motherboard, video card, hard drive and other components in a large case. The monitor, keyboard, and other peripherals connect wirelessly or with cables. Whether the case sits vertically or horizontally, it has lots of space for add-in cards, cables and air circulation.

A laptop, however, is much smaller and lighter than even the most compact PC tower. Its screen is an integrated part of the unit, as is its keyboard. Instead of a spacious case with lots of room for air circulation, a laptop uses a small, flat design in which all the pieces fit together snugly.

Because of this fundamental design difference and because of a laptop's inherent portability, components have to:

Fit into a compact space

Conserve power

Produce less heat than desktop components

Often, these differences make the components more expensive, which can contribute to higher laptop prices.

In the following sections, we'll examine how laptops handle these differences.

Processor

The microprocessor, or CPU, works with the operating system to control the computer. It essentially acts as the computer's brain. The CPU produces a lot of heat, so a desktop computer uses circulating air, a fan and a heat sink -- a system of plates, channels and radiator fins used to draw heat off of the processor -- to cool off. Since a laptop has far less room for each of these cooling methods, its CPU usually:

Runs at a lower voltage and clock speed -- This reduces heat output and power consumption but slows the processor down. Most laptops also run at a higher voltage and clock speed when plugged in, and at lower settings when using the battery.

Mounts to the motherboard without using pins -- Pins and sockets take up a lot of room in desktop PCs. Some motherboard processors mount directly to the motherboard without the use of a socket. Others use a Micro-FCBGA (Flip Chip Ball Grid Array), which uses balls instead of pins. These designs save space, but in some cases mean that the processor cannot be removed from the motherboard for replacement or upgrading.

Has a sleep or slow-down mode -- The 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. The Apple G4 processor also prioritizes data to minimize battery drain.

Some laptops use desktop CPUs that are set to run at lower clock speeds. Although this can improve performance, these laptops typically run much hotter and have a significantly reduced battery life.

Laptops usually have small fans, heat sinks, heat spreaders or heat pipes to help dissipate the heat from the CPU. Some higher end laptop models reduce heat even further with liquid coolant kept in channels alongside the heat pipe. Also, most laptop CPUs are near the edge of the unit. This allows the fan to move the heat directly to the outside instead of across other components.

Memory and Storage

A laptop's memory can make up for some of the reduced performance that comes from a slower processor. Some laptops have cache memory on or very near the CPU, allowing it to access data more quickly. Some also have larger busses, allowing data to move between the processor, motherboard and memory more quickly.

Laptops often use smaller memory modules to save space. Memory types used in laptops include:

Small Outline Dual Inline Memory Module (SODIMM)

Dual Data Rate Synchronous RAM (DDR SDRAM)

Single data rate Synchronous RAM (SDRAM)

Proprietary memory modules

Some laptops have upgradeable memory and feature removable panels for easy access to the memory modules.

Like a desktop, a laptop has an internal hard disk drive, which stores the operating system, applications and data files. However, laptops generally have less disk space than desktops. A laptop hard drive is also physically smaller than that of a desktop. In addition, most laptop hard drives spin more slowly than desktop hard drives, reducing both heat and power consumption.

Desktop computers have multiple bays for installing additional drives, such as CD and DVD ROM drives. However, space in a laptop is in much shorter supply. Many laptops use a modular design, allowing a variety of drives to fit in the same bay. These drives come in three different designations:

Hot swappable - The computer can stay on while changing the drive.

Warm swappable - The computer can stay on while changing the drive, but the corresponding bus (the path the drive uses to send data to the CPU) must be inactive.

Cold swappable - The computer must be off during the swap.

In some cases, these drive bays are not just limited to drives but will also accept extra batteries.