Notes

Processing and Memory on the Motherboard
The main processing functions of your computer take place in the CPU and memory, both of which reside on your computer’s motherboard. In the following sections, we’ll explore the components of the motherboard and how memory helps your computer process data.

The Motherboard and Memory
Objective 2.9 Describe the functions of the motherboard and RAM.

What exactly is a motherboard? The motherboard is the main circuit board that contains the central electronic components of the computing device, including the computer’s processor (CPU), its memory, and the many circuit boards that help the computer function. On a desktop, the motherboard (see Figure 2.32) is located inside the system unit, the metal or plastic case that also houses the power source and all the storage devices (such as the hard drive). In a laptop, tablet, or phone, the system unit is combined with the monitor and the keyboard into a single package. Portable devices also have motherboards, but they are smaller, flatter, and lack expansion slots (see the image of the cell phone motherboard in Figure 2.5.).

Motherboard has labeling for Memory slots, CPU socket, expansion slots, ports.
Figure 2.32 A motherboard for a desktop computer contains the socket for the computer’s processor (CPU), slots for memory (RAM) modules, ports, and slots for expansion cards.
Source: GIGA-BYTE Technology Co., Ltd.

What exactly is RAM? Random access memory (RAM) is the place in a computer where the programs and data that the computer is currently using are stored. RAM is much faster to read from and write to than the hard drive and other forms of storage. The processor can request the RAM’s contents, which can be located, opened, and delivered to the CPU for processing in a few nanoseconds (billionths of a second). If you look at a desktop motherboard, you’ll see RAM as a series of small cards (called memory cards or memory modules) plugged into slots on the motherboard.

Because the entire contents of RAM are erased when you turn off the device, RAM is a temporary or volatile storage location. To save data permanently, you need to save it to your hard drive or to another permanent storage location, such as a flash drive or cloud storage.

Does the motherboard contain any other kinds of memory besides RAM? In addition to RAM, the motherboard contains a form of memory called read-only memory (ROM). ROM holds all the instructions the device needs to start up when it’s powered on. Unlike data stored in RAM, which is volatile storage, the instructions stored in ROM are permanent, making ROM a nonvolatile storage location, which means the data isn’t erased when the power is turned off.

What other functionality is contained on the motherboard? The motherboard on desktop computers also includes slots for expansion cards (or adapter cards), which are circuit boards that provide additional functionality. Typical expansion cards found in the system unit are sound and video cards. A sound card provides a connection for the speakers and microphone, whereas a video card provides a connection for the monitor. High-end gaming desktops use expansion cards to provide video and sound capabilities, making it easy for owners to upgrade to the latest video cards on the market. Laptops, tablets, and phones have video and sound capabilities integrated into their motherboards.

Other parts of the motherboard provide a means for network and Internet connections. A network interface card (NIC), which enables your computer to connect with other computers or to a cable modem to facilitate a high-speed Internet connection, is often integrated into the motherboard. Wireless network interface modules provide connectivity to WiFi networks. And connectivity ports such as USB and Thunderbolt ports are also integrated into the motherboard.

On cell phone motherboards you’ll also find a GPS (global positioning system) receiver, which is used to receive radio waves from satellites that help you pinpoint your location. The GPS receivers were initially installed in cell phones to allow the 911 emergency call operators to pinpoint the location of cell phones for people needing assistance. However, now many location-dependent apps, like Google Maps and Pokémon Go, make use of the GPS information.

How does GPS work? Built and operated by the U.S. Department of Defense, the global positioning system (GPS) is a network of 24 satellites (plus 3 working spares) that constantly orbit Earth. GPS receivers use an antenna to pick up the signals from these satellites and use special software to transform those signals into latitude and longitude. Using the information obtained from the satellites, GPS receivers determine geographical location anywhere on the planet to within 3 feet. The exact accuracy depends on such things as atmospheric conditions and interference from obstacles like mountains or buildings.Processing
Objective 2.10 Explain the main functions of the CPU.

What is the CPU? As noted earlier, the central processing unit (CPU or processor) is sometimes referred to as the “brains” of the computer because it controls all the functions performed by the computer’s other components and processes all the commands issued to it by software instructions.

How is processor speed measured? Processor speed is measured in units of hertz (Hz). Hertz is a measurement of machine cycles per second. A machine cycle is the process of the CPU getting the data or instructions from RAM and decoding the instructions into something the computer can understand. Once the CPU has decoded the instructions, it executes them and stores the result back in system memory. Current systems run at speeds measured in gigahertz (GHz) or billions of machine cycles per second. Therefore, a 3.8 GHz processor performs work at a rate of 3.8 billion machine cycles per second. Modern CPUs can perform as many as tens of billions of tasks per second without error, making them extremely powerful components. It’s important to realize, however, that CPU processor speed alone doesn’t determine the performance of the CPU.

What else determines processor performance? Although speed is an important consideration when determining processor performance, CPU performance is also affected by other factors. One factor is the number of cores, or processing paths, a processor has. Initially, processors could handle only one instruction at a time. Now, processors are designed so that they can have two, four, or even ten different paths, allowing them to process more than one instruction at a time (see Figure 2.33). Applications such as virus protection software and the operating system, which are always running behind the scenes, can have their own processor paths, freeing up the other paths to run other applications such as a web browser, Word, or iTunes more efficiently.

Diagram of single-core and dual-core for CPU for program 1 and 2.
Figure 2.33 With multi-core processors, CPUs can work in parallel, processing two or more separate programs at the same time instead of switching back and forth between them.
How can I tell what processor is best for me? The “best” processor will depend on your particular needs and is not always the processor with the highest processor speed and the greatest number of cores. Intel, one of the leading manufacturers of computer processor chips, has created a pictorial rating system for CPU chips. Intel provides a website (ark.intel.com) that assists in comparing the performance of different models of CPUs.Storing Data and Information
Because RAM is volatile storage, it can’t be used to store information indefinitely. To save your data and information permanently, you need to save it to a nonvolatile storage device, such as a hard drive, cloud storage location, DVD, or flash drive.

Storage Options on Computing Devices
Objective 2.11 Describe the various means of storing data and information with computing devices.

Local Storage Devices
Are there different kinds of hard drives? The hard disk drive (HDD or hard drive) is your desktop’s or laptop’s primary device for permanent storage of software and documents. The hard drive is a nonvolatile storage device. (Note that because of space limitations, tablets and phones do not have hard drives. The nonvolatile storage used in these devices is various types of memory chips.)

An internal hard drive resides within the desktop or laptop system unit and usually holds all permanently stored programs and data. Today’s internal hard drives (see Figure 2.34) have capacities of as much as 8 TB or more. External hard drives offer similar storage capacities but reside outside the system unit and connect to the computer via a port.

Photo shows internal structure of hard drive.
Figure 2.34 Internal hard drives (shown here open . . . normally they are sealed) are a desktop and laptop computer’s primary nonvolatile storage.
Source: Mbongo/Fotolia

The most common type of hard drive has moveable parts—spinning platters and a moving arm with a read/write head—that can fail and lead to disk failure. However, the solid-state drive (SSD) is now a popular option for ultrabooks and laptop storage. SSDs have no moving parts, so they’re more efficient, run with no noise, emit little heat, and require little power. In addition, they’re less likely to fail after being bumped or dropped. Replacing a conventional hard drive in an older laptop with an SSD can often significantly improve the computer’s performance.

Permanent storage devices are located in your desktop or laptop computer in a space called a drive bay. There are two kinds of drive bays:

Internal drive bays cannot be seen or accessed from outside the system unit. Generally, internal drive bays are reserved for internal hard drives.

External drive bays can be seen and accessed from outside the system unit. External drive bays house DVD and Blu-ray drives, for example. On desktop computers, sometimes there are empty external drive bays that can be used to install additional drives. These extra spaces are covered by a faceplate on the front panel. Laptop computers generally do not give you the ability to add additional drives. Such expansion is done by attaching an external drive to the computer through a USB port.

Portable Storage Options
How can I take my files with me? For large portable storage needs, there are portable external hard drives that are small enough to fit into your pocket and that have storage capacities of 4 TB (or more). These devices are lightweight and enclosed in a protective case. They attach to your computer via a USB port (see Figure 2.35).

Photo shows mobile connected to port of a laptop through cable.
Figure 2.35 Smaller, portable external hard drives enable you to take a significant amount of data and programs on the road with you.
Source: Inga Nielsen/Shutterstock

A flash drive (sometimes referred to as a jump drive, USB drive, or thumb drive) uses solid-state flash memory, storing information on an internal memory chip. When you plug a flash drive into your computer’s USB port, it appears in the operating system as another disk drive. You can write data to it or read data from it as you would a hard drive. Because a flash drive contains no moving parts, it’s quite durable. It’s also tiny enough to fit in your pocket. Despite their size, flash drives can have significant storage capacity—currently as much as 1 TB or more. Often, flash drives are combined with other devices such as pens or keychains for added convenience.

Another convenient means of portable storage is a flash memory card, such as an SD card. Like the flash drive, memory cards use solid-state flash memory. Most desktops and laptops include slots for flash memory cards, but if your computer is not equipped, there are memory card readers that you can plug into a USB port. Flash memory cards let you transfer digital data between your computer and devices such as digital cameras, smartphones, tablets, video cameras, and printers. Although incredibly small—some are even smaller than a postage stamp—these memory cards have capacities that exceed the capacity of a DVD. Figure 2.36 compares the storage capacities of hard drives and flash drives.

Figure 2.36 Hard Drive and Flash Drive Storage Capacity

(Scanrail1/Shutterstock; Ruslan Ivantsov/Shutterstock; D. Hurst/Alamy Stock Photo; Cphoto/ Fotolia; Zuma Press/Alamy Stock Photo)

Hard Drive and Flash Drive Storage Capacity


Drive Type Typical Capacity
Solid-state drive (SSD) 1 TB or more
External portable hard drive 4 TB or more
Mechanical internal hard drive 8 TB or more
Flash drive 1 TB or more
Flash memory card 128 GB
How does my cell phone store data? Today’s cell phones use various combinations of memory chips to store data. They do not contain hard drives.

Can I increase the storage capacity of my smartphone? Many smartphones let you add additional memory through micro SD flash cards (see Figure 2.37). Micro SD cards are easy to install inside a phone, and some models have external slots for an SD card. Not all smartphones allow memory upgrades in this way, however. For example, iPhones don’t allow you to add memory.

Photo shows SD card of scale measured as 1.5 cm.
Figure 2.37 Micro SD flash cards add memory to some phones.
Source: digitalr/123RF

Cloud Storage
How can I easily access my files from different devices? You may use multiple devices, such as a smartphone, laptop, and a tablet, at different times. Invariably, you’ll need access to a file that is stored on a device other than the one you’re using. If your devices are connected to the Internet, cloud storage provides a convenient option.

Cloud storage refers to using a service that keeps your files on the Internet (in the “cloud”) rather than storing your files solely on a device. Using a cloud storage service requires that you install software or an app on your device. Popular cloud storage options include Google Drive, Microsoft’s OneDrive, and Dropbox. For example, after installing the Dropbox software on your devices, any files you save in the Dropbox folder are accessible by all your other devices via the Internet. You can also share folders in Dropbox with other Dropbox users, making it ideal for group collaboration.

Most cloud storage providers give users an option of some amount of free storage, but the amount of space varies. All cloud storage providers offer additional storage space for a fee.

Optical Storage
What other kinds of storage devices are available? Most desktop and all-in-one computers come with at least one optical drive that can read from and maybe even write to CDs, DVDs, or Blu-ray discs. As we have moved toward streaming media services and cloud-based delivery of software, optical drives have not been included in laptops and ultrabooks to save weight and space. However, if you still need to use optical drives, inexpensive portable drives that attach via USB ports are readily available.

Data is saved to optical discs as tiny pits that are burned into the disc by a high-speed laser. Compact discs (CDs) were initially created to store audio files. Digital video (or versatile) discs (DVDs) are the same size and shape as CDs but can store up to 14 times more data.

What if you want even more storage capacity? Blu-ray discs (BDs), which are similar in size and shape to CDs and DVDs, can hold as much as 50 GB of data—enough to hold approximately 4.5 hours of movies in HD digital format. Many desktop systems are now available with BD-ROM drives and Blu-ray burners. Figure 2.39 shows the storage capacities of the various optical storage media.

Medium Type Typical Capacity
Blu-ray (dual layer) 50 GB
Blu-ray 25 GB
DVD DL (dual layer) 8.5 GB
DVD 4.7 GB
CD 700 MB
Figure 2.39 Optical Storage Media Capacities