Cache memory is a special type of high performance memory used by processors to speed up processing by avoiding access to slower main memory. Cache memory is built into the processor itself and operates at the same speed as the rest of the processor, as opposed to main memory which has to be several times slower.
Having a bigger cache will in most cases result in faster performance. Currently, processor cache sizes up to 8 megabytes are available.
Centrino Mobile Technology is a collection of computer parts from Intel which when combined comprise the Centrino platform. To be Centrino compliant, a laptop should incorporate one of a range of Centrino certified processors, chipsets and wireless networking cards. Centrino certified laptops run cooler, have longer battery lives and are expected to work with a wider range of wireless hotspots than other laptops.
Laptops come equipped with liquid crystal displays built into their lids. They can range in size all the way from 6 inches for a netbook to 20 inches for a large desktop-replacement class laptop. Display size is given as the distance from one diagonal corner to the other, so a 15 inch display measures 15 inches from its bottom left corner to its top right corner.
A docking station is a more sophisticated version of a port replicator. It allows you to easily connect a laptop to a set of external devices such as a monitor, keyboard, mouse, printer, etc in a single operation, rather than hooking them each up individually. However, a docking station may also provide additional functionality such as extra hard drive space, extra optical drives, additional connectors not available on the laptop itself and so on. Docking stations usually also include a power supply so that you don't have to run off batteries while using one.
ExpressCard is a standard for expansion cards. The cards themselves bear some similarity to the older PC Cards, but are slightly narrower and come in an L shape (for the 54mm variant), or substantially narrower (for the 34mm variant). Both the 34mm and 54mm variants use the same connector and the 34mm cards can plug into slots of either size (the 54mm cards are too big to fit into 34mm slots). ExpressCards allow a laptop to be expanded with devices such as Flash memory card readers, networking cards, wireless cards, extra USB ports and other devices. ExpressCards are hot-pluggable, meaning that they can be safely connected or disconnected from a laptop without turning it off first.
Hard drives are data storage devices built into every computer. You can think of them as being like the computer's filing cabinet, a place where files can be kept for later retrieval. Any program you install on a computer and any file you create will be stored on the hard drive. The drive contains a metal disc with a magnetic coating, spinning at high speed. Data is stored on the disc in a similar manner to how sound and video is recorded onto video tape. Because hard drives are used to store all the data a computer works with they are considered to be a vital part of the system.
The amount of space that a hard drive can use to store files is measured in gigabytes (billions of bytes). One gigabyte (1 GB) is about the same amount of storage as one and a half recordable CDs. A typical music file such as one downloaded from iTunes or Amazon is about 5 megabytes, and there are a thousand megabytes in a gigabyte, so 1 GB is enough for around 200 music files.
As hard drives store everything you work with on your computer, the size of your hard drive is of critical importance - you can never have too much hard drive space. A 20 GB drive, considered a good size only a few years ago, is now thought to be too small to be of much use. Even the cheapest computers currently come with at least an 80 GB drive. For laptops, hard drive size can typically range from 120 GB to 200 GB, though larger sizes are available.
Solid State Drive
Recently a new storage technology has appeared, called Solid State Drives, or SSD for short. Instead of a spinning magnetic disc, these drives use Flash memory chips to store data. Flash memory doesn't lose its contents when it is powered off, making it suitable for storing files. SSDs have several key advantages over mechanical hard drives; they have no moving parts to damage or wear out, making them more likely to survive being dropped. They also use less power, generate less heat and are usually faster than mechanical drives, and are silent in operation. However, they are more expensive than mechanical hard drives, and don't offer as much storage space. The biggest SSDs top out at 128-256 GB, compared to up to 1500 GB for mechanical drives.
The video controller is a part of your computer that generates the image that will be displayed on the computer's monitor. In laptops you can buy systems with either a video controller integrated into the chipset or wit ha more capable dedicated video controller chip.
Most discrete video controllers are made by nVidia or ATI/AMD, whereas integrated controllers are typically made by Intel. If you need high performance for tasks like video editing, or want to play games on your laptop, then a discrete graphics solution would be a better choice. For general computing tasks such as email, web browsing, word processing, etc, integrated graphics are more than adequate.
An Integrated Graphics Controller is a video controller that is built into the computer's chipset itself and which uses a portion of the computer's main memory as a frame buffer. Integrated graphics are common on mainstream laptops, as they have the advantage of costing less, generating less heat and using less power than discrete video controllers, resulting in cooler running laptops with longer battery lives. They can't match the performance of a dedicated solution though, and the portion of the main memory they use as a frame buffer cannot be used for general tasks by the computer, reducing the amount of memory available to the system.
A small number of laptops, such as Apple's MacBook, include both kinds of video controller and allow you to select which one to use. This lets you trade performance for battery life depending on your need at the time.
Discrete graphics controller
A discrete graphics controller is an extra chip installed in a laptop whose sole responsibility is managing the display. They also have special dedicated video memory that is separate from the main memory of the rest of the computer. Discrete graphics controllers are more common in high end high performance laptops, as they offer superior performance compared to integrated graphics and don't take memory away from the rest of the system. The performance comes at a price though, as they are more expensive than integrated controllers and produce more heat. They also have higher power demands than integrated controllers, resulting in shorter battery life.
Memory is the main working space your computer uses to load running programs and files that you are working on. Computer memory is volatile, meaning that once you turn the computer's power off, you will lose anything that is stored in memory. This is why computers also have hard drives to provide a place for you to keep files when you are not working on them.
The amount of memory a system has is measured in megabytes and gigabytes, like hard drive space. However, due to technical reasons, a gigabyte of computer memory is about 7% more than a gigabyte of hard drive space.
The amount of memory you have will affect how well your computer will run. If a computer doesn't have enough real memory to load a program or open a file it will allocate space on the hard drive to act as "virtual memory" and move parts of memory that aren't being used very often off onto it in order to free space for whatever you want to do. However, if you then decide to switch back to something that was moved out of memory, the computer will have to copy it back into main memory from the hard drive. This "paging out" and "paging in" process can slow a computer down noticeably, and the less real memory you have, the more reliant on virtual memory your computer will be and the slower it will run.
Modern computer software is heavily reliant on memory, for example the minimum memory required for Windows Vista is 512 megabytes (half a gigabyte). This won't leave much real memory available though, and your computer will be heavily reliant on virtual memory. You can avoid this problem by installing more memory, at least a gigabyte is recommended for Vista
Almost all laptops will support networking in one form or another. This can include wired ethernet, wireless networking or both. Some newer machines also incorporate 3G cellular broadband to allow internet access over the cellular telephone network. Accessing the internet will require networking, and with portable computers such as laptops the flexibility that wireless offers is often the better choice.
Wireless networking equipment (also often referred to as wi-fi) will support some version of the 802.11 standard, either the mainstream 802.11g or a draft version of the new 802.11n standard (sometimes called n draft). You may also find 802.11a systems, which offer similar performance to 802.11g, but these are rather uncommon. Systems based on 802.11b are generally considered to be obsolete. All versions of 802.11 require you to be within range of a wireless hotspot or router for internet access.
If you have no access to a hotspot then the new 3G Broadband features of several new laptops wil allow you to access the internet over the cellular telephone network, thus allowing you to get internet access nearly anywhere in the world covered by mobile phone networks. As with a mobile phone, you will need a contract with your mobile phone operator who will provide you with a SIM card to install in your laptop. If your laptop doesn't support 3G broadband then most mobile phone operators can provide a USB "dongle" you can attach to your laptop for 3G access.
An optical drive is a device built into many laptops that allows you to access or create CDs, DVDs, and/or Blu-Ray discs, depending on the capabilities of the drive. Nearly all drives can read CDs, and most can write ("burn") them. Drives that can read and write DVDs are also common.
Newer high-end laptops may come with a drive capable of reading Blu-Ray discs, the latest format for high definition movies.
Some types of laptop, such as netbooks and Apple's Macbook Air don't have an optical drive at all because there is not enough space to install one. An external optical drive can be purchased for the Macbook Air as an optional accessory
PC Card (also known as PCMCIA or CardBus) is a standard for expansion cards. The cards themselves are similar in dimensions to credit cards, though they are considerably thicker. PC cards allow a laptop to be expanded with devices such as Flash memory card readers, networking cards, wireless cards, extra USB ports and other devices. PC Cards are hot-pluggable, meaning that they can be safely connected or disconnected from a laptop without turning it off first.
PC Cards have been superseded by ExpressCards and are considered a legacy technology.
Ports and Connectors
Most laptops will incorporate at least 2 USB ports, as there is a very wide range of accessories that can connect via USB, such as external hard drives, Flash memory sticks, 3G broadband dongles, keyboards, mice and many other types of devices. As USB devices are so common, many laptop designs will include more than 2 ports.
Laptops will also have one video connector of some sort to allow them to be used with full sized monitors, projectors, or other display devices. Most machines will have a VGA port or a more modern DVI port. Some laptops made by Apple will have a mini-DVI port or a mini DisplayPort connector for this job.
Laptops with sound will usually have a headphone jack for listening in private, and will often also incorporate a microphone jack as well. Some may also include S/PDIF connectors for connecting to high end audio equipment.
Some laptops have an IEEE 1394 port, also known as a FireWire port, or for laptops made by Sony an iLink connector. This can be used to connect to external hard drives, several models of video cameras and other computers via their FireWire link
A port replicator is a laptop accessory that helps you quickly connect your laptop to a veriety of external devices, such as a monitor, keyboard, mouse, printer and so on. Port replicators make this job easier as all the devices can be connected in one go rather than one at a time. Docking stations are similar, but offer additional features.
The processor is a computer's "brain", responsible for all the operations the computer can perform. The performance of the processor will have a significant impact on the performance of the computer as a whole.
Atom is a new family of processors from Intel intended for use in ultra-portable laptops such as netbooks. It is designed with extremely low power-consumption in mind.
Celeron is the branding Intel uses for a range of lower cost processors for use in value computers.
Core 2 is the branding Intel applies to its current range of processors. The range includes Core 2 Duo for mainstream systems, Core 2 Quad for higher performance computers and Core 2 Extreme for workstations. The Core 2 Duo processors consist of 2 separate processors in a single package and the Quad and Extreme versions include 4
Core i7 is Intel's latest range of processors, the successor to the current range of Core 2 processors. All the current members of the Core i7 family are quad core, meaning that they effectively contain four separate processors in a single package. Core i7 is expected to offer better performance than the current Core 2 family.
Pentium is the branding Intel uses for a range of lower cost processors for use in value computers. This name had previously been used for Intel's mainstream and high performance processors, but these roles have now been taken by the Core 2 and Core i7 range
Semperon is the brand name AMD uses for a series of low cost processors intended for use in value products. Semperon processors can be found in many low cost computers and are in direct competition with Intel's Celeron range.
Turion is a brand name AMD uses for a series of high performance mobile intended for use in high performance laptops. Turion processors can be found in several higher specification laptops and are in direct competition with Intel's Core 2 Duo processors
Swappable Drive Bay
Laptops that include optical drives may either have the drive built directly into the computer itself, or install the drive in a "plug-in" module so it can be removed. In the latter case, the drive could be replaced with a different device or an extra battery, depending on the design of the laptop in question. A fixed drive generally saves some space and makes the computer more robust, while a removable drive offers more flexibility over fixed drives