• microprocessor
• operating system
• solid-state memory
• disk drives
• input/output ports
• sound cards and speakers

Microprocessors
Like standard desktops, laptops are powered by microprocessors. The microprocessor is the brain of the laptop and coordinates all of the computer's functions according to programmed instructions (that is, the operating system software). The DX-4 processor shown in the photo below is no longer used, but it is typical of modern laptop microprocessors in that it is customized for laptop use. A typical laptop processor has features that reduce power consumption and heat. For example, laptop processors often run at a lower voltage and often have multiple sleep or slow-down modes that significantly increase battery life. Typical laptop microprocessors include Motorola's PowerPC family (used in Apple Macintosh computers), Intel's Pentium and Celeron families (used in PCs) and AMD's K5 and K6 families (used in PCs).

Close-up of the Toshiba's Intel 486 DX4 microprocessor. This microprocessor is no longer used in laptop computers.

Operating Systems
The operating system is the set of pre-programmed instructions that tell the microprocessor what to do. Operating systems on laptops include Windows 98/2000/NT (Microsoft) and Mac OS, depending upon the type of computer (PC vs. Mac), and Linux (Linux is not an option for most consumers, but some third-party developers are writing applications for this operating system on laptops).

Memory
Laptops have memory , both RAM and ROM, just like desktops. The laptop's ROM chip contains the BIOS just as it does in a desktop computer. (See How Bios Works for details.) RAM stores the application software and data files while the computer is on. RAM differs on a laptop in that it uses a different form factor -- that is, the size and shape of the modules that carry the RAM. Manufacturers have to build laptops to be portable (smaller) and to withstand more jostling (durable) than a desktop would ever get, so the memory modules have to be different. While some laptops use a standard Small Outline Dual Inline Memory Module (SODIMM), others use the manufacturer's proprietary memory modules. Most laptops should have at least 64 MB of RAM to have sufficient memory to run operating systems and applications software. Also, some laptops allow you to upgrade the memory of your computer and come equipped with convenient access panels to plug in additional memory chips.

Access panel to the memory chips on the laptop's underside.

Close-up of Toshiba's memory chips.

Disk Drives
Like desktops, laptops have various disk drive storage devices. All laptops have an internal hard disk drive, usually 6 to 20 gigabytes (GB). The hard disk drive stores operating systems, application programs and data files. Although the hard disk drive works the same in a laptop as it does in a desktop, laptops generally have less disk space than desktops and you will have fewer choices for hard disk drives in laptops. The smaller hard disk space is one of the chief limitations of laptops.

Close-up of Toshiba's hard drive.

Close-up of Toshiba's CD-ROM drive.

In addition to hard drives, most laptops have some type of removable disk storage system, such as floppy disks, Zip disks, compact discs (CD) and DVDs. There are three options for disk drives in laptops:

• Some laptops have more than one bay built into the case for disk drives (such as floppy drive and CD-ROM drive).
• Some laptops have one bay that you can swap or interchange various drives. You just pull one drive out and put another in:
  • "cold-swappable" drive - You must turn the computer off, change drives, then reboot the computer.
  • "hot-swappable" drive - You can change the drives without turning the computer off. This feature saves you the time involved in restarting the computer.
• Some laptops have no internal drives. All drives are external and connected to the computer by cables. This feature allows the laptop to be very small and thin.

Input/Output Ports
Computers need to talk to other devices (such as printers, modems and networks). Computers send and receive information through various input/output ports, which can include serial ports, parallel ports and Universal Serial Bus (USB) ports.

The back panel of the Toshiba Satellite Pro laptop computer, showing the various input/output ports.

In addition to ports, some laptops have expansion slots for PCMCIA standard adapter cards (Type I and Type II) or "PC " cards. These cards can be used to upgrade your laptop by adding memory, a modem, a network connection or a peripheral device (for example, a CD-ROM drive).

The Toshiba Satellite Pro has a PC card for modem/Ethernet connections.

Sound Cards and Speakers
Like desktops, most laptops are equipped with sound cards and speakers so they can play music from CDs. However, the quality of the speakers built into most laptops does not match that of speakers for desktops, because space is a major limitation in a laptop case. The Toshiba laptop that we dissected has a sound card and jacks so you could hook up a microphone or headphones; it also has a small speaker for sound.

Sound card of the Toshiba Satellite Pro laptop.