CENTRAL PROCESSING UNIT

Central processing unit (CPU) – Laptop CPUs have advanced power-saving features and produce less heat than desktop processors, but are not as powerful.There is a wide range of CPUs designed for laptops available from Intel (Pentium M, Celeron M, Intel Core and Core 2 Duo), AMD (Athlon, Turion 64, and Sempron), VIA Technologies, Transmeta and others. On the non-x86 architectures, Motorola and IBM produced the chips for the former PowerPC-based Apple laptops (iBook and PowerBook). Some laptops have removable CPUs, although support by the motherboard may be restricted to the specific models. In other laptops the CPU is soldered on the motherboard and is non-replaceable. [Photo] [Photo] A SODIMM memory module. Memory (RAM) – SO-DIMM memory modules that are usually found in laptops are about half the size of desktop DIMMs. They may be accessible from the bottom of the laptop for ease of upgrading, or placed in locations not intended for user replacement such as between the keyboard and the motherboard. Currently, most midrange laptops are factory equipped with 3-4 GB of DDR2 RAM, while some higher end notebooks feature up to 8 GB of DDR3 memory. Netbooks however, are commonly equipped with only 1 GB of RAM to keep manufacturing costs low. Expansion cards – A PC Card (formerly PCMCIA) or ExpressCard bay for expansion cards is often present on laptops to allow adding and removing functionality, even when the laptop is powered on. Some subsystems (such as Ethernet, Wi-Fi, or a cellular modem) can be implemented as replaceable internal expansion cards, usually accessible under an access cover on the bottom of the laptop. Two popular standards for such cards are MiniPCI and its successor, the PCI Express Mini. Power supply – Laptops are typically powered by an internal rechargeable battery that is charged using an external power supply. The power supply can charge the battery and power the laptop simultaneously; when the battery is fully charged, the laptop continues to run on AC power. The charger adds about 400 grams (1 lb) to the overall "transport weight" of the notebook. Battery – Current laptops utilize lithium ion batteries, with more recent models using the new lithium polymer technology. These two technologies have largely replaced the older nickel metal-hydride batteries. Typical battery life for standard laptops is two to five hours of light-duty use, but may drop to as little as one hour when doing power-intensive tasks. A battery's performance gradually decreases with time, leading to an eventual replacement in one to three years, depending on the charging and discharging pattern. This large-capacity main battery should not be confused with the much smaller battery nearly all computers use to run the real-time clock and to store the BIOS configuration in the CMOS memory when the computer is off. Lithium-ion batteries do not have a memory effect as older batteries may have. The memory effect happens when one does not use a battery to its fullest extent, then recharges the battery. New innovations in laptops and batteries have seen new possible matchings which can provide up to a full 24 hours of continued operation, assuming average power consumption levels. An example of this is the HP EliteBook 6930p when used with its ultra-capacity battery. Video display controller – On standard laptops the video controller is usually integrated into the chipset. This tends to limit the use of laptops for gaming and entertainment, two fields which have constantly escalating hardware demands. Higher-end laptops and desktop replacements in particular often come with dedicated graphics processors on the motherboard or as an internal expansion card. These mobile graphics processors are comparable in performance to mainstream desktop graphic accelerator boards. Display – Most modern laptops feature 12 inches (30 cm) or larger color active matrix displays with resolutions of 1024×768 pixels and above. Many current models use screens with higher resolution than typical for desktop PCs (for example, the 1440×900 resolution of a 15" Macbook Pro can be found on 19" widescreen desktop monitors). [Photo] [Photo] A size comparison of 3.5" and 2.5" hard disk drives Removable media drives – A DVD/CD reader/writer drive is typically standard. CD drives are becoming rare, while Blu-Ray is becoming more common on notebooks.Many ultraportables and netbooks either move the removable media drive into the docking station or exclude it altogether. Internal storage – Laptop hard disks are physically smaller—2.5 inches (64 mm) or 1.8 inches (46 mm) —compared to desktop 3.5 inches (89 mm) drives. Some newer laptops (usually ultraportables) employ more expensive, but faster, lighter and power-efficient flash memory-based SSDs instead. Currently, 250 to 320 GB sizes are common for laptop hard disks (64 to 128 GB for SSDs). Input – A pointing stick, touchpad or both are used to control the position of the cursor on the screen, and an integrated keyboard is used for typing. An external keyboard and/or mouse may be connected using USB or PS/2 (if present). Ports – several USB ports, an external monitor port (VGA or DVI), audio in/out, and an Ethernet network port are found on most laptops. Less common are legacy ports such as a PS/2 keyboard/mouse port, serial port or a parallel port. S-video or composite video ports are more common on consumer-oriented notebooks. Docking stations A docking station is a relatively bulky laptop accessory that contains multiple ports, expansion slots and bays for fixed or removable drives. A laptop connects and disconnects easily to a docking station, typically through a single large proprietary connector. A port replicator is a simplified docking station that only provides connections from the laptop to input/output ports. Both docking stations and port replicators are intended to be used at a permanent working place (a desk) to offer instant connection to multiple input/output devices and to extend a laptop's capabilities. Docking stations became a common laptop accessory in the early 1990s. The most common use was in a corporate computing environment where the company had standardized on a common network card and this same card was placed into the docking station. These stations were very large and quite expensive. As the need for additional storage and expansion slots became less critical because of the high integration inside the laptop, the "port replicator" has gained popularity. The port replicator was a cheaper, often passive device that simply mated to the connectors on the back of the notebook and allowed the user to quickly connect his laptop so that his monitor, keyboard, printer and other devices were instantly attached. As higher speed ports such as USB and Firewire became common, the connection of a port replicator to a laptop was accomplished by a small cable connected to one of the USB or FireWire ports on the notebook. Wireless Port Replicators are available as well. A recent variant of the port replicator is the combined power/display/USB hub cable found in the new Apple Cinema Display. [edit] Standards Some laptop components (optical drives, hard drives, memory and internal expansion cards) are relatively standardized, and it is possible to upgrade or replace them in many laptops as long as the new part is of the same type. Subtle incompatibilities and variations in dimensions, however, are not uncommon. Depending on the manufacturer and model, a laptop may range from having several standard, easily customizable and upgradeable parts to a proprietary design that can't be reconfigured at all. In general, components other than the four categories listed above are not intended to be replaceable, and thus rarely follow a standard. In particular, motherboards, locations of ports, design and placement of internal components are usually make- and model-specific. Those parts are neither interchangeable with parts from other manufacturers nor upgradeable. If broken or damaged, they must be substituted with an exact replacement part. The users uneducated in the relevant fields are those the most affected by incompatibilities, especially if they attempt to connect their laptops with incompatible hardware or power adapters. Intel, Asus, Compal, Quanta and other laptop manufacturers have created the Common Building Block standard for laptop parts to address some of the inefficiencies caused by the lack of standards.Advantages Laptop computers are portable and can be used in many locations. Shown here is former Mexican president Vicente Fox. Portability is usually the first feature mentioned in any comparison of laptops versus desktop PCs. Portability means that a laptop can be used in many places—not only at home and at the office, but also during commuting and flights, in coffee shops, in lecture halls and libraries, at clients' location or at a meeting room, etc. The portability feature offers several distinct advantages: Getting more done – Using a laptop in places where a desktop PC can't be used, and at times that would otherwise be wasted. For example, an office worker managing his e-mails during an hour-long commute by train, or a student doing her homework at the university coffee shop during a break between lectures Immediacy – Carrying a laptop means having instant access to various information, personal and work files. Immediacy allows better collaboration between coworkers or students, as a laptop can be flipped open to present a problem or a solution anytime, anywhere. Up-to-date information – If a person has more than one desktop PC, a problem of synchronization arises: changes made on one computer are not automatically propagated to the others. There are ways to resolve this problem, including physical transfer of updated files (using a USB stick or CDs) or using synchronization software over the Internet. However, using a single laptop at both locations avoids the problem entirely, as the files exist in a single location and are always up-to-date. Connectivity – A proliferation of Wi-Fi wireless networks and cellular broadband data services (HSDPA, EVDO and others) combined with a near-ubiquitous support by laptops means that a laptop can have easy Internet and local network connectivity while remaining mobile. Wi-Fi networks and laptop programs are especially widespread at university campuses. Other advantages of laptops include: Size – Laptops are smaller than standard PCs. This is beneficial when space is at a premium, for example in small apartments and student dorms. When not in use, a laptop can be closed and put away. Low power consumption – Laptops are several times more power-efficient than desktops. A typical laptop uses 20-90 W, compared to 100-800 W for desktops. This could be particularly beneficial for businesses (which run hundreds of personal computers, multiplying the potential savings) and homes where there is a computer running 24/7 (such as a home media server, print server, etc.) Quiet – Laptops are often quieter than desktops, due both to the components (quieter, slower 2.5-inch hard drives) and to less heat production leading to use of fewer and slower cooling fans. Battery – a charged laptop can run several hours in case of a power outage and is not affected by short power interruptions and brownouts. A desktop PC needs a to handle short interruptions, brownouts and spikes; achieving on-battery time of more than 20–30 minutes for a desktop PC requires a large and expensive UPS