Mobile computing components

The rapid growth in the PC industry in the 1980s soon led to a demand for portability, and by the middle of the decade PC manufacturers had begun releasing products to meet this demand. Since then, the mobile PC market has been a key driver for continuous innovation, miniaturization and technological advancement.

This has largely been in a number of technological areas of particular relevance to the mobile arena:

  • In screen technology, the dramatic weight, size, and power consumption benefits of flat panels has, for several years, outweighed their relatively high cost and long been a driver for developments in LCD technology and, for several years, outweighed their relatively high cost.
  • In battery technology, the ever-increasing consumption of more powerful mobile CPUs has required continuous improvements simply to enable average battery life to remain fairly constant.
  • In storage technology, the innovation of PC Card technology has met the demand for smaller, lighter, and more portable tools for information processing.

The basic components of laptops function similarly to their desktop counterparts, but are miniaturized, adapted to mobile use. The design bounds on power, size, and cooling of laptops limit the maximum performance of laptop parts compared to that of desktop components.

The following list summarizes the differences and distinguishing features of laptop components in comparison to desktop personal computer parts:

Laptop Motherboard

Motherboard: A motherboard, also known as a mainboard, system board, or logic boards on Apple Computers, and sometimes abbreviated as mobo is the central or primary circuit board making up a complex electronic system, such as a modern computer.

Laptop motherboards are highly make and model specific, and do not conform to a desktop form factor. Unlike a desktop board that usually has several slots for expansion cards (3 to 7 are common), a board for a small, highly integrated laptop may have no expansion slots at all, with all the functionality implemented on the motherboard itself; the only expansion possible in this case is via an external port such as USB. Other boards may have one or more standard, such as ExpressCard, or proprietary expansion slots. Several other functions (storage controllers, networking, sound card and external ports) are implemented on the motherboard.

While most desktop computers use one of these motherboard form factors, laptop (notebook) computers generally use highly integrated, customized and miniaturized motherboards designed by the manufacturers. This is one of the reasons that notebook computers are difficult to upgrade and expensive to repair – often the failure of one integrated component requires the replacement of the entire motherboard, which is also more expensive than a regular motherboard due to the large number of integrated components in it.

Laptop CPU

Central processing unit (CPU): The heart of any computer is the processor or CPU for short (central processing unit). A notebook processor is a CPU optimized for notebook computers. 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, Core 2 Duo, solo, and quad) and Intel Atom; AMD (Athlon, Turion 64, and Sempron); VIA Technologies, Transmeta and others. On non-x86 architectures, Motorola and IBM produced the chips for the former PowerPC-based Apple laptops (iBook and PowerBook). Most laptops have removable CPUs, although the motherboard may restrict the processor to the specific models, limiting the processors that are compatible. Some laptops use a desktop processor instead of the laptop version and have high-performance gains at the cost of the potential for overheating problems, and less battery life. In other laptops, the CPU is soldered on the motherboard and is non-replaceable.

Laptop cooling unit

Cooling: Despite laptop processors giving off less heat than their desktop counterparts, they still need cooling. Waste heat from operation is difficult to remove in the compact internal space of a laptop. Early laptops used heat sinks placed directly on the components to be cooled, but when these hot components are deep inside the device, a large space-wasting air duct is needed to exhaust the heat. Modern laptops instead rely on heat pipes to rapidly move waste heat towards the edges of the device, to allow for a much smaller and compact fan and heat sink cooling system. Waste heat is usually exhausted away from the device operator, towards the rear or sides of the device. Multiple air intake paths are used since some intakes can be blocked, such as when the device is placed on a soft conforming surface like a chair cushion. It is believed that some designs with metal cases, like Apple’s aluminum MacBook Pro and MacBook Air, also employ the case of the machine as a “gigantic” heat sink, allowing it to supplement cooling by dissipating heat out of the device core. Secondary device temperature monitoring may reduce performance or trigger an emergency shutdown if it is unable to dissipate heat, such as if the laptop were to be left running and placed inside a carrying case. Such a condition has the potential to melt plastics or ignite a fire.

2GB SO-DIMM module

SODIMM memory module (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 mid-range laptops are factory equipped with 3–4 GB of DDR2 RAM, while some higher-end notebooks (usually mobile engineering workstations) feature up to 32 GB of DDR3 memory. Netbooks are commonly equipped with only 1 GB of RAM and generally only expandable to 2 GB, if at all, to keep manufacturing costs low.

Always check to make sure upgrading the memory yourself will not void any warranty, get the right type, and check the manual or manufacturers’ website for proper upgrade instructions.

Installing RAM

The different types of SO-DIMMs can be recognized at a glance by the distinctive notches used to “key” them for different applications: 100-pin SO-DIMMs have two notches, 144-pin SO-DIMMs have a single notch near (but not at) the center, and 200-pin SO-DIMMs have a single notch nearer to one side.

SO-DIMMs are more or less equal in power and voltage to DIMMs, and as memory technology moves forward, both SO-DIMMs and DIMMs are available in equal speed (PC3200, for example, and clock speeds such as 2.0, 2.5 and 3.0 CAS latency) and capacity (512MB, 1GB, etc.).

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 internal subsystems such as Ethernet, Wi-Fi, or a wireless 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. In newer laptops, it is not uncommon to also see a Mini SATA (mSATA) connection in addition to MiniPCI and PCI Express Mini.

Laptop Power Supply

Power supply: Laptops are typically powered by an internal rechargeable battery that is charged using an external power supply, which outputs a DC voltage typically in the range of 7.2– 24 volts. The power supply is connected to the laptop through an AC connector cable. It can charge the battery and power the laptop simultaneously; when the battery is fully charged, the laptop continues to run on power supplied by the external power supply. The charger adds about 400 grams (1 lb) to the overall “transport weight” of the notebook.

The complete range of power supplies is very broad, and could be considered to include all forms of energy conversion from one form into another. Conventionally though, the term is usually confined to electrical or mechanical energy supplies. Constraints that commonly affect power supplies are the amount of power they can supply, how long they can supply it for without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulses.

The voltage regulation of power supplies is done by incorporating circuitry to tightly control the output voltage and/or current of the power supply to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply’s output, or any reasonable voltage variation at the power supply’s input.

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 or less 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 CMOS 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. Innovations in laptops and batteries have seen situations which the battery can provide up to 24 hours of continued operation, assuming average power consumption levels. An example is the HP EliteBook 6930p when used with its ultra-capacity battery.

Video display controller: A Graphics Processing Unit or GPU (also occasionally called Visual Processing Unit or VPU) is a dedicated graphics rendering device for a personal computer, workstation, or game console. On standard laptops the video controller is usually integrated into the chipset to conserve power. This tends to limit the use of laptops for gaming and entertainment. These two fields have constantly escalated hardware demands, and because the integrated chipset is very difficult to upgrade for a standard user, laptops may grow obsolete quickly for use in gaming and entertainment. 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 low-end mainstream desktop graphic accelerator boards. A few notebooks have switchable graphics with both an integrated and discrete card installed. The user can choose between using integrated graphics when battery life is important and dedicated graphics when demanding applications call for it. This allows for greater flexibility and also conserves power when not required.

Display: Most modern laptops feature 13 inches (33 cm) or larger color active matrix displays based on CCFL or LED lighting with resolutions of 1280×800 (16:10) or 1366 × 768 (16:9) pixels and above. Some models use screens with resolutions common in desktop PCs (for example, 1440×900, 1600×900 and 1680×1050.) Models with LED-based lighting offer lesser power consumption, and often higher brightness. Netbooks with a 10 inches (25 cm) or smaller screen typically use a resolution of 1024×600, while netbooks and subnotebooks with a 11.6 inches (29 cm) or 12 inches (30 cm) screen use standard notebook resolutions. Having a higher resolution display will allow more items to fit onscreen at a time, improving the user’s ability to multitask.

Storage: Laptops commonly use 2.5″ hard disk drives, which are much smaller than desktop hard drives. Removable media drives: A DVD/CD reader/writer drive is nearly universal on full-sized models, and is common on thin-and-light models; it is uncommon on subnotebooks and unknown on netbooks. CD drives are becoming rare, while Blu-ray is becoming more common on notebooks.

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 500 GB sizes are common for laptop hard disks (64 to 512 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 port, or Bluetooth (if present).