The basics:

A first look on the main external components of a laptop: "A picture worth a thousand words".

   

                                                                                               Batteries


 
In a brief, the internal components of a laptop:

Processor:  A
central processing unit controls the functions of most electronic products. Usually called a CPU, this component accepts input data, processes information and sends it to whatever component that is in charge of executing the action. CPUs are also known as microprocessors and are at the center of any computer system. Although CPUs are most often thought of as a computer chip, they can also be found in many other electronic devices including cell phones,handheld devices, microwaves, television sets and toys.

                                       

 

The laptop processor is typically a lower-powered processor than those found in similar desktop machines, although some laptop makers have used desktop processors in their laptops to get a performance edge. Processors designed for mobile computing generally consume less power, and thus run cooler than desktop processors. This is important because you want your battery to last a long time and you also don’t want to burn a hole through your lap. Desktop PCs typically have massive heat-sinks and fans to cool them down, but it’s hard to fit that stuff into a tiny laptop, and fans drain laptop batteries quickly.

A useful term to understand is Thermal Design Power, or TDP. This indicates the maximum amount of wattage that the cooling solution for that processor will need to dissipate. It’s not like it will always dissipate that amount of wattage, but, generally, if you want a cooler processor, go for the lowest TDP you can get.



Memory: The term memory identifies data storage that comes in the form of chips, and the word storage is used for memory that exists on tapes or disks. Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual chips capable of holding data. Some computers also use virtual memory, which expands physical memory onto a hard disk.
Every computer comes with a certain amount of physical memory, usually referred to as main memory or RAM (random access memory). You can think of main memory as an array of boxes, each of which can hold a single byte of information. A computer that has 1 megabyte of memory, therefore, can hold about 1 million bytes (or characters) of information.


 

Determining if it has enough memory is to look at the requirements of the software you intend to run. Pick up the boxes for each of the applications and the OS that you intend to run and look at both the minimum and recommended requirements. Typically you want to have more RAM than the highest minimum and ideally at least as much as the highest listed recommended requirement. A general idea of how a system will run with various amounts of memory:
  • Minimum: 2GB
  • Optimal: 4GB
  • Best: 8GB

The ranges provided are a generalization based upon most common computing tasks. It is best to check the requirements of the intended software to make the final decisions. This is not accurate for all computer tasks because some operating systems use more memory than others.

It should be noted that netbooks typically come with just a single gigabyte of memory and the Windows 7 operating system. This is the true bare minimum of the operating system to function but it isn't really ideal. It is best to upgrade them to 2GB of memory in order to achieve their true performance levels which is very important to consider when looking at them and discussed in more detail later.

Many laptops also use integrated graphics controllers that use a portion of the general system RAM for the graphics. This can reduce the amount of available system RAM from 64 to 512MB depending upon the graphics controller. If the system is using an integrated graphics controller it is best to get a bit more memory to compensate for this.

Hard Disk Drive: When the power to a PC is switched off, the contents of memory are lost. It is the PC’s hard disk that serves as a non-volatile, bulk storage medium and as the repository for a user’s documents, files and applications.

 

Now, let´s talk about what is inside the Hard Disk Drive...
Basically is one or more disks resembling a DVD divided by tracks and sectors and a moving head to read/write the data on the surface.
The tracks could be considered like guides for where the data should be placed on the hard drive.
The sectors are logical segments or groups where the 1s and 0s are stored. This allows the disk head to skip over data that it doesn’t need to read.

  


The optical drive unit (CD/DVD/Blu-ray): It´s a disk drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from discs, but actually the drives are commonly both readers and recorders, also called burners or writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by such drives. Optical drive is the generic name; drives are usually described as "CD" "DVD", or "Blu-Ray", followed by "drive", "writer", etc.



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. 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.

Laptop lithium CMOS Battery: This small battery has a fundamental function that is to run the real-time clock and to store the BIOS configuration in the CMOS memory when the computer is off.

DC Power Jack: It´s simply the jack that connects the external power supply/adapter to the battery through several diodes. It is a common weak spot on most laptops. If someone trips on the wire while you have the power adaptor plugged into your laptop, chances are that the power jack will get damaged.

On most laptops the DC power jack is soldered directly to the motherboard and there are only three or four small pins holding it in place. Unfortunately that makes the power jack quite weak. Any sideways pulling of the DC power cord while attached to the laptop will usually dislodge at least one of these pins, breaking the solder around it. Modern laptops use quite a lot of power, from about 70W to 120W or even more. The bad electrical connection from the dislodged pin will cause sparks and heating that will eventually burn a hole through the motherboard and can even be a fire hazard.