|Battery Types and Installation|
|Using a Docking Station|
|PCMCIA and PC Cards|
Servicing these unique computers requires a skill set beyond what is necessary to service desktop computers. Every portable computer, even between different models from the same vendor, is slightly different. In this chapter, we discuss some of the many components that are unique to the world of portable computing.
Battery Types and InstallationsBecause manufacturers are constantly driven to make components smaller and smaller, very few standards exist in the world of the portable. As a result, portable computers are all very proprietary. Steps are being taken to make components more interoperable, but we are still a long way from where the desktop PC industry is in terms of standards. Some components are not even compatible between different portable computers from the same vendor. Also, repairs and upgrades to portable computers remain much more expensive compared to desktop PCs.
As with the rest of the computer industry, portable computer technology is rapidly evolving. Almost as soon as one technology is released, another is released behind it, rendering the old technology obsolete.
|Pros of a laptop||Cons of a laptop|
|All-in-one components||Less bang for the buck|
|Ability to use docking stations||Easily dropped|
|Does not take up much space||Harder to repair|
|Better resale value||Components are more expensive|
|Screen image is not as good|
|Not as upgradable|
|Limited space physically limits expansion|
|Hardware and drivers more difficult to find|
|Mouse and keyboard may be hard to use|
|Limited battery life|
|May not work until it's thawed if left in the cold|
Nickel Cadmium, or NiCad, batteries are rarely used in portable computers today. NiCad batteries must be recharged more often than other batteries, and a full recharge can take as much as 12 hours. Furthermore, when a NiCad battery is recharged before it is fully discharged, the battery loses the ability to fully recharge again. This symptom is known as the memory effect. NiCad batteries also contain Cadmium, which is highly toxic. NiCad batteries are limited to about 1000 recharges.
Nickel/Metal Hydride, or NiMH, batteries offer several advantages over NiCad batteries. Compared to the same size NiCad, a NiMH battery can produce 33-50 percent more power. Advances in NiMH technologies have all but erased the memory effect. NiMH batteries are also more environmentally friendly because they do not contain heavy metals.
Lithium Ion, or LiIon, are the best computer batteries commercially available. LiIon batteries, although slightly more expensive that NiMH batteries, offer many advantages. A smaller, lighter LiIon battery can produce more power than a NiMH battery. LiIon batteries are also becoming available in high-end cellular phones and video camcorders.
Exam Watch: Portable computer batteries must be disposed of properly. Check the label of the battery and with local agencies for disposal directions. Do not just throw batteries in the trash!Installation of batteries in portables is easy for the end user, as demonstrated in Figure 6-1. Many people buy a second battery that they keep charged to use as a spare. Most batteries either install from the bottom or the side. Many have an easy-to-remove plastic cover that must be removed first. Generally, there is a row of contacts on the battery itself that meet with spring loaded contacts inside the computer. If a battery is not charging properly, it may help to clean these contacts.
Click Here To View Figure 6-1: Installing a portable system batteryIf you replace a battery in a portable computer, do not just throw it away! Consult your local waste management company to find out local requirements for battery disposal.
With many different types of batteries available, which one should you use? LiIon is the best choice if it is available, although it is slightly more expensive. NiMH is more common and less expensive, but is slightly heavier and produces less power. Stay away from NiCad batteries if at all possible.
AC adapters for different models and manufacturers of computers have varying output voltage. Before testing, check with the manufacturer to determine the proper voltage. If a computer is not charging properly, it is easy to replace the AC adapter with another and see if that solves the problem.
Portable DisplaysPortable displays have come a long way from where they were ten years ago. Older portable computers actually used a Cathode Ray Tube (CRT) for a display. These behemoths were about the size of a small suitcase! Imagine, having a ‘portable’ computer that is too big to fit in the overhead bin on an airplane. Fortunately, we now have flat liquid crystal displays (LCD) that are much thinner, lighter, and require much less power than the small CRTs from ten years ago.
Two major types of LCD displays dominate the market in laptop computers today. The major differences between the two are in the quality of the image displayed, the amount of power used, and the cost of manufacturing.
Passive matrix displays make up the bulk of the laptop displays today. They are cheaper to produce and draw far less power than active matrix displays. Passive matrix displays are easily recognized by poor display quality when viewing the screen from an angle.
Passive matrix displays are made of a grid of horizontal and vertical wires. At the end of each wire is a transistor. In order to light a pixel at (X, Y), a signal is sent to the X and Y transistors. In turn, these transistors then send voltage down the wire, which turns on the LCD at the intersection of the two wires.
Passive matrix screens have problems with images that change quickly. This is very apparent when a cursor is moved quickly across the screen. The cursor will fade from view, and then appear again once the movement has stopped. In fact, Microsoft added the mouse trails option primarily so people wouldn’t lose their cursors on passive matrix displays.
Active Matrix displays provide much better image quality at the expense of higher energy consumption and higher cost. Active matrix displays are based on Thin Film Transistor technology (TFT). Instead of having two rows of transistors, active matrix displays have a transistor at every pixel. This allows much quicker display changes and produces display quality comparable to a CRT.
Just like a traditional CRT display, LCD displays need to be cleaned often. This should be done with a damp cloth or a cleaner specifically designed for cleaning computer displays. Be careful not to drip moisture into the keyboard or other parts of the portable when cleaning the display, as it may have undesirable results.
LCD displays are not a serviceable part. If a LCD display is damaged or broken, it must be replaced. This can be extremely expensive, as the parts will need to come from the original manufacturer. Active matrix screens can easily cost more than $1,000 to replace.
Normally, if a user wanted to use an external monitor, keyboard, or mouse, they would have to plug each one into the portable computer every time that they wished to use it. They would also need to have the appropriate connector available on the portable itself. Then, when they wanted to take the portable computer with them when they left, they would have to unplug all of the peripherals they were using. This is both cumbersome and inconvenient.
A docking station allows a user to install their monitor, external keyboard, and mouse to the docking station. Then, whenever they wish to use these peripherals, they can simply connect their portable computer to the docking station. This is a much more convenient and easy way for users to use full-size peripherals when in the office.
Some operating systems (OSs), such as Windows 95, automatically detect when the portable computer is installed with a docking station. The OS can then use the appropriate hardware settings and user preferences for your docking station. This is extremely convenient, especially for changing screen resolutions for different displays.
Port replicators are the cheapest and simplest version of the three types of docking stations. Most portable computers have external VGA, keyboard, and serial connections. Port replicators simply provide a copy of the interfaces that already exist on the back of the portable computer. Port replicators often ship with a second power cable so the user can leave it plugged into the port replicator. Port replicators are generally the least expensive way to add these types of capabilities to your portable, and for most people this is more than enough.
Enhanced port replicators extend the capabilities of port replicators slightly by adding interfaces not available in the portable computer alone. Extended port replicators often add enhanced sound capabilities and more PC Card slots.
A true docking station gives your portable the greatest amount of expandability and power. Docking stations can give your portable all of the same capabilities usually found in a desktop computer. In addition to everything you get with an enhanced port replicator, docking stations may add ISA slots, PCI slots, and SCSI or EIDE capabilities. They may also provide for full-size drive bays for installing full-size hard drives and CD-ROM drives.
A portable computer that has docking capabilities usually does so via a proprietary interface somewhere on the back. Unfortunately, this means that a docking station for one computer will usually not work with a different type of computer, even from the same manufacturer.
Each manufacturer provides slightly different features with their docking stations, and some features available from one manufacturer may not be available from another. Please consult your manufacturer’s guidelines for installing a docking station. Figure 6-2 shows what a docking station typically looks like.
Click Here To View Figure 6-2: A portable computer and a docking station
Replacing a hard drive in portable computer is generally easy. For most portables, simply follow the steps in Exercise 6-1.
Exercise 6-1 Replacing a Hard Drive
- Usually there is a small plastic cover underneath the computer that must be removed.
- Once the cover has been removed, a few screws usually hold in the hard drive.
- Be careful not to bend the male connectors when removing the hard drive.
- Insert the new hard drive, again being careful not to bend the connectors.
- Replace the screws.
- Replace the cover.
Click Here To View Figure 6-3: Removing a hard drive from a portable system
The 1.0 version of the PCMCIA specification was released in June 1990 and was originally intended only for memory cards. PCMCIA version 1.0 defined the 68-pin interface that we currently use as well as the physical specifications for the Type I and Type II cards.
The 2.x releases of the PCMCIA standards expanded the features of the same 68-pin interface and added support for Type III PC Cards. Type III cards are generally reserved for rotating mass storage, such as hard drives. PCMCIA 2.x is backward compatible with PCMCIA 1.0 PC Cards.
In 1995, PCMCIA released the latest standard, officially using the name "PC Card." All PCMCIA cards are now referred to as PC Cards. This latest specification added support for DMA, Bus Mastering, Zoomed Video (ZV), and 32-bit CardBus operation. ZV is a direct data connection between a PC Card and host system that allows a PC Card to write video data directly to the video controller. The 32-bit CardBus specification allows speeds of up to 133 Mbps at 33MHz.
The PC Card specification defines PC Cards as having a length of 85.6 mm and a width of 54.0 mm. Type I cards are the thinnest, measuring only 3.3 mm thick and a generally only used for memory. Type II cards are 5.0 mm thick and are generally used for I/O devices such as modems, network adapters, or SCSI adapters. Type III cards are 10.5 mm thick and are usually used for mass storage devices such as removable hard drives. Most portable computers now come with at least one Type III slot built-in.
Exam Watch: All PC Cards are 85.6 mm by 54.0 mm. Type I cards are 3.3 mm thick, Type II are 5.0 mm thick, and Type III 10.5 mm thickWindows 95 supports hot-swapping PC Card devices. This means that you can swap PC Card devices without rebooting your computer. Windows NT currently does not support this feature.
Socket Services is a layer of BIOS level software that isolates PC Card software from the computer hardware and detects the insertion or removal of PC Cards.
Card Services software manages the allocation of system resources automatically, such as memory and interrupts once the Socket Services software detects that a card has been inserted in the PC Card slot.
If your operating system does not come with support for PC Card services, check with the manufacturer for support.
The PCMCIA is continuing to develop new technologies for PC Cards. PC Cards are also useful in other electronic devices besides computers. Many digital cameras now use PC Cards for storage.
Uses for PC Cards today include:
|Cellular phone interface|
|Smart Card readers|
|Ethernet LAN adapters|
|GPS (Global Positioning System) cards|
|Modem/ethernet combination cards|
|Parallel port interface|
|Sound cards, input, and output|
|Token ring LAN adapter cards|
Click Here To View Figure 6-4: Installing a PC Card in a portable system
The manufacturer should provide documentation on installing additional memory. This is generally a simple task. An example is shown in Figure 6-5.
Click Here To View Figure 6-5: Installing portable computer memoryShould the memory on the motherboard itself go bad, it may be necessary to replace the entire motherboard.
Trackballs contain the greatest amount of moving parts and require the most maintenance. As the trackball is rotated inside its case, it constantly picks up dust and oils. This dirt and grime builds up inside the rollers and eventually impairs the trackball movement. This can be cleaned in that same manner as an opto-mechanical mouse. First, the ring holding the trackball must be removed. Rotating the ring counter-clockwise usually does this. Once removed, the trackball can be lifted out.
The type of pointing device that you choose comes down to two things: availability and personal preference. I personally prefer the pointing stick, but many people prefer touch pads and track balls.
|Some portable system components are not compatible between different portable computers from the same vendor.|
|Type I PC Cards are generally only used for memory.|
|Port replicators are the cheapest and simplest version of the three types of docking stations.|
|Portable computer batteries must be disposed of properly. Check the label of the battery and with local agencies for disposal directions. Do no just throw batteries in the trash.|
|Passive matrix displays make up the bulk of the laptop displays today.|
|Most portables have some RAM on the motherboard, but manufacturers usually provide a proprietary expansion slot for additional RAM.|
|Microsoft added the mouse trails option primarily so people wouldn’t lose their cursors on passive matrix displays.|
|Be careful not to drip moisture into the keyboard or other parts of the portable when cleaning the display, as it may have undesirable results.|
|A docking station allows a user to install their monitor, external keyboard, and mouse to the docking station rather than to their portable system.|
|Type III PC Cards are generally reserved for rotating mass storage, such as hard drives.|
|When a NiCad battery is recharged before it is fully discharged, the battery loses the ability to fully recharge again, which is known as the memory effect.|
|All PCMCIA cards are now referred to as PC Cards.|
|All PC Cards are 85.6 mm by 54.0 mm. Type I cards are 3.3 mm thick, Type II are 5.0 mm thick, and Type III 10.5 mm thick.|
|Socket Services is a layer of BIOS level software that isolates PC Card software from the computer hardware and detects the insertion or removal of PC Cards.|
|Touch pad mice are quickly becoming the pointing device of choice with portable computers.|
|Type II PC Cards are generally used for I/O devices such as modems, network adapters, or SCSI adapters.|