IT Vocab Chapter 3
Bluetooth
Bluetooth is a short-range wireless communication technology used by many devices. It uses radio waves that operate between 2.4 and 2.485 GHz. Most Bluetooth devices have a range of about 30 feet. Bluetooth is able to operate without a direct line of sight between devices. This means there can be an obstruction between devices such as thin walls.This versatility has made Bluetooth the short-range communication method of choice for devices like wireless headphones, speakers, keyboards, mice, smart watches, printers, and game controllers.
Compression
A way of making data consume less storage space. For example, if an uncompressed file has fifty zeros in a row, a compression algorithm could encode the data as fifty zeros instead of recording each individual zero.Compressed files are much more efficient than uncompressed files.
Flash Storage
A compact, portable storage device that uses special memory chips to store data.
Inkjet printer
A printer that sprays small dots of ink from an ink reservoir onto a sheet of paper.
Orange
Subwoofer and center-out. Used with 5.1 surround sound systems.
Pink
Microphone
Black
Rear sound speaker for 5.1 and 7.1 systems - output.
Network Client
A device that can connect to a network. All of the above devices can be network clients.
PCI with AGP
AGP is similar to PCI, but designed specifically for graphics support. Motherboards that provide AGP support have a single AGP slot. AGP is commonly used for video cards in modern computer systems, but has been replaced by PCIe.
Files
All data on a storage medium, such as a hard disk or flash drive, is encoded as a single enormous list of ones and zeroes. A file is a group of ones and zeroes that are organized together.
Power
Each component requires electricity, the bus provides this power.
Lime Green
Line-out. Used for front speakers and headphones. Used with 5.1 surround sound systems.
Memory location
Memory is a major component in a computer system, as it temporarily stores the data while its needed for processing. The bus keeps track of the address or location where the data is stored in the memory.
RJ-45
Most computers provide a Registered Jack 45 (RJ-45) connector that allows you to connect the system to a network.
Solid state devices (SSD)
Some desktop and laptop systems replace the traditional internal hard disk drive with a special type of flash storage called an SSD. SSDs are much faster and more durable than hard disk drives. The downside is that they're much more expensive. For this reason, many desktop computers use a small SSD for the operating system and programs and a large HDD for storing files.Some computers use what is called a dual-drive hybrid system where a computer includes both a SSD and HDD. There is also Solid-state hybrid drive (SSHD). It has a single drive with both a SSD and HDD installed in the same drive and uses only one connection to the motherboard.SSDs use a 2.5 form factor and can be connected to the motherboard using DATA or peripheral component interconnect express (PCIe) adapter cards (depending on the disk). PCIe is preferred, as it provides a faster connection than the SATA connection.
Light Blue
Stereo line-in.
Permissions
The actions (read, write, move, delete, etc.) users can perform on a file. File systems use an Access Control List (ACL) to specify which users can perform which tasks for each file and folder in the system.
Naming rules
The character set that a files system allows for filenames. For example, NTFS reserved for special purposes the characters \ / : * ? < > |. It doesn't allow these characters in file names.The ext4 file system, by contrast, allows all character except / to be used in a filename. Most file systems reserve characters like \ / : for system use.
Hard Disk Drive (HDD)
The most common type of long-term storage that uses thick magnetic disks encased in a protective housing to store data.
Encryption
The process of converting information so it cannot be understood without decrypting it using a key, especially to prevent unauthorized access.
File Format
The way a file is organized. File formats are indicated by an extension such as .jpg, .gif, .png., .mp3, .wav, .wma, .mp4, .avi, and .wmv.
Microphone
To record audio, a microphone can be connected to a desktop system using a USB connector, an audio jack, or a wireless connection.Laptops and mobile devices already have integrated microphones and are less likely to have an external microphone attached.
USB Type A
Universal Serial Bus (USB) Type A connectors are rectangular in shape. One end is typically plugged directly into the computer. The other is plugged into a peripheral device. They are designed for devices that may be plugged in and out frequently, such as: Keyboards Mice Cameras Flash drives External hard drives
Printer
You use a printer to create a hard copy of the information processed by the computer. Data is sent through a wire or over radio waves to a printer. The printer receives the data, formats it, and transfers it onto a piece of paper.Printers are commonly connected using a USB port, a FireWire port, or a network connection.
Basic PCIe
provides one lane for transmission (x1), at a transfer rate of 250 MBps. It can also provide multiple transmission lanes (x2, x4, x8, x16, x32). Newer versions of PCIe can transfer data at an even higher rate per lane:Version 1: 250 MBpsVersion 2: 500 MBpsVersion 3: 1 GBpsVersion 4: 2 GBps In addition to greatly increased speed, PCIe offers higher quality service. PCIe is backwards compatible and allows legacy PCI technology to be run in the same system (i.e. you can have both PCIe and PCI buses in the same system). PCIe buses are most commonly used for video cards in modern computer systems, although nearly any other device can be designed for a PCIe slot.
Camera shutter
A camera component that sits between the lens and the sensor, allowing light to enter for a short time.
Video Graphics Array (VGA) connector
A connector, identified by its blue color and three rows of pins, that is used to connect older monitors to a computer.
Optical Drive
A storage device that uses light instead of magnetism to store information. This include CD-ROM, DVD, and Blu-ray devices.
Expansion Cards
An expansion card is a circuit board that connects to a computer's motherboard. The expansion board gives the motherboard additional power or functionality.
Digital Camera
Digital cameras and webcams can be connected to input digital images and video into the system. These devices are commonly connected to desktops and laptops using a USB, FireWire, or wireless connection.Mobile devices already include integrated cameras, so they are not commonly used with external digital cameras and webcams. Webcams are most often installed in a laptop, just above the screen. The quality of webcams differs greatly from model to model, but can have a resolutions as low as 25 frames per second (fps) or a high definition resolution as high as 60 or more fps. Digital cameras can also include such devices as a phone or a hand-held camera (used for taking pictures). These devices store their images on a memory card, also known as a flash card, CompactFlash, or Secure Digital (SD) card.Some computers include the ability to plug the devices directly into a computer, letting you copy images from the device. If the memory card can be removed, computers often have a way to plug the memory chip into the computer directly or through a USB adapter. Many of the newer devices even support transferring data using wireless technology.
Gray
Middle surround speakers for 7.1 systems.
Compression
Reencoding a file to consume less storage space.
Mobile Device
Small computing devices such as tablets and smart phones that are much more portable than desktops and laptops.
PCI
The Peripheral Component Interconnect, or PCI, is an older technology but can still be found in many computers. The PCI bus is usually 32-bits wide, although 64-bit versions were used as well. Running at 33 MHz, it can transfer data at 133 MB/s (or 266 MB/s for 64-bit versions).
File sharing
The ability of users to allow other users to perform specified tasks (such as read or write) to files. File sharing can usually be accomplished more efficiently using the cloud. Most file systems allow users to share folders saved on their hard drive with users who are connected to the same local network.This type of file sharing is known as Peer-to-Peer (P2P) sharing. Microsoft Workgroups are a form of P2P. It can facilitate collaborative team projects. A drawback to local file sharing is that access is cut off when someone powers off the system that has the shared file.P2P can also be used to share files online. To do this, you install peer-to-peer software (such as Gnutella, Xunlei, Bittorrent, etc.) and use it to locate and share files.If you are not using cloud sharing, the best solution is to set up a network share, which is a shared folder on a network server that is always available.
Data
The data is the information that is transferred between the components in the computer.
File System
The methods and structures that an operating system uses to organize files on a storage device like a hard drive. File systems often use directory structures to keep track of files.
Drive
The top-level folder, or directory, of a file system.
Fragmentation
When parts of a single file, program, or application are stored in different areas of a physical disk.
PC Repair Technician
A PC repair technician does exactly what the name implies: they repair PCs. This includes both software and hardware issues. A typical day for a PC Repair Technician involves installing, troubleshooting, servicing, and repairing devices such as desktop computers, laptops, tablets, printers, as well as network equipment such as routers, switches, cables and related network hardware. Great customer service is essential in this job because it includes constant interaction with people who encounter computer problems. Being able to handle these situations calmly and professionally is what the job is all about. In addition to confidence in troubleshooting computer systems, an important skill for this job is the ability to train others. Repair technicians often need to instruct users on how use their personal computers and networks. To be qualified for a job like this, many employers ask for at least an industry certification.
Universal Serial Bus (USB)
A common interface used to connect peripherals, such as mice, keyboards, printers, and digital cameras to a computer.
Clock timing
A computer has an clock mechanism, often performed by the CPU, which synchronizes how all the components work together over the bus.
Gaming consoles
A computer system specifically built to be operated by a gaming pad instead of a keyboard and mouse. Gaming consoles are also referred to as gaming box or video game console .A gaming console includes the major computer components, such as CPU, GPU, RAM, an operating system, disk storage, etc. These components, however, are designed to work best with games and the high graphics capabilities required by these games. Another difference is that gaming consoles often use a high-definition TV for its screen or display. Example of gaming consoles include, Xbox, PlayStation, Nintendo Switch, and Wii.
Hybrid laptop devices
A computer that caters to the needs of both tablet and laptop users. Hybrid laptops provide a touchscreen and other tablet-style conveniences, but also provide an operating system and keyboard.Hybrid laptops are often referred to as "2-in-1" devices. These systems have several advantages. They: Can run standard laptop operating systems. Have laptop type processors. Have a touch screen that provides an dimension not available on a standard laptop.
Servers
A computer whose purpose is to provide shared disk storage or to perform a special service for a large number of people, such as web processing, email, or database services. As such, this is not something you would typically have in your home or would use for personal use. Servers are widely used in business. Although each server is different, most servers use many of the same components that a desktop or client computer uses. However, servers typically have more memory, disk space, and processing power than a desktop computer.
High-Definition Multimedia Interface (HDMI) connector
A connector now available on a wide variety of devices such as computers, monitors, TVs, Blu-Ray players, and more. HDMI is used to transfer high-definition signals. It supports both audio and video data.
Digital Visual Interface (DVI) connector
A connector, typically white with three rows of eight pins, designed to connect digital monitors to a computer.
All-in-one device
A desktop computer that contains every component except the keyboard and mouse in the same case as the monitor. All-in-one systems have several advantages: They require less space than a desktop. They are easy to move to a new location. All-in-one systems also have some disadvantages: They are harder and more expensive to repair. If any component (other than the keyboard or mouse) goes bad, you will probably have to take it into a shop to get repaired. In most cases, you are not able to expand the memory or disk space. However, external drives can still be added using USB ports.
Peripheral
A device, usually external to a computer, that is plugged into a computer's communication port or is connected wirelessly. Common peripherals are keyboards, mice, monitors, speakers, and printers.
Touch screen
A display device that allows a user to interact with a computer by touching, tapping, and swiping areas on the screen.
Heat Sink
A heat sink is a term for a component that disperses heat from another object. In computers, a heat sink attaches to a chip (like a CPU) and prevents it from overheating by transferring its heat to a fluid medium such as air or liquid. Often, air cooling is used with a heat sink to help move heat away from the CPU. The performance of the heat sink can be affected by many factors such as air velocity, material choice, and fin design. Because of the bulky size of a heat sink, laptops typically use heat spreaders instead of heat sinks for cooling. Heat spreaders are installed next to a large flat surface. Heat spreaders do not cool the CPU themselves, rather they spread the heat from the CPU out against the large flat surface to allow the heat to dissipate. Heat spreaders have no fins or fans like the heat sinks below which makes them ideal for slim laptops.
Keyboard
A keyboard allows you to send alphanumeric information to the system by pressing keys. When you press a key, the corresponding character is sent to the computer hardware. The software running on the system then does whatever it has been programmed to do with that keystroke.Key point regarding keyboards are: External keyboards are required for desktop systems, but are optional for laptop and mobile devices that use integrated keyboards or on-screen keyboards. For desktop and laptop systems, keyboards typically connect using a USB port, but they can also be connected wirelessly. External keyboards can be connected to mobile devices using a wireless connection. Not all keyboards have the same layout of keys. There are many variations in where each letter or symbol may be placed on the keyboard. For example, in German, additional letters use the spaces commonly used by the ; ' [ and = keys on a typical US English keyboard. The operating system can typically be mapped to multiple keyboard layouts.In Windows 10, you press Start + Spacebar to use the keyboard shortcut to quickly switch between keyboard layouts.These settings can also be set using the Settings app by selecting Date & time, and then selecting Region.Control Panel also provides the ability to set the region.Some keyboard settings can be customized using the Settings app by selecting the Ease of Access option and then selecting Keyboard.Windows 10 also includes other settings that can be configured through the Control Panel and Keyboard. With this method, you can configure such things as the repeat delay, repeat rate, the cursor blink rate.
Photosensitive material
A light sensitive surface used to capture the image focused by the lens.
Water Cooling
A liquid-cooled system places a water-cooled heat exchanger near the heat source. This exchanger then removes the heat and reduces the air temperature. Because of water's higher density, liquid cooling can efficiently absorb heat. Water cooling also provides lower power consumption. Fan speeds are decreased because they don't have to move a large amount of air. This also lowers the system's noise levels and power consumption.
Network Cards
A network interface card (NIC) enables a device to connect to a network. Many modern computers have a built-in NIC, but also have the option to add additional NICs to expand the functionality of the system. A NIC connects the device to the network through a RJ-45 port that connects to an unshielded twisted pair cable, as shown in the following graphic.
Desktop
A popular type of computer system that can be equipped with peripheral devices such as a monitor, keyboard, mouse, and speakers.
Laser printer
A printer that uses electrical charges and heat to fuse tiny plastic particles (called toner) to the paper.
Bluetooth
A short-range wireless communication technology used to connect peripherals such as wireless headphones, speakers, keyboards, mice, smart watches, printers, and game controllers to a computer, including smartphones.
Notebook/Laptop
A small computer that combines a display and keyboard and is designed to be easily carried.
Defragmentation
A utility in which all fragmented files on a drive are found and reconsolidated into the same physical location on the disk.
Video Cards
A video card, also called a display or graphics card, is used to enhance the quality of images shown on a display. Rendering images requires a lot of processing power. A video card acts like an extra CPU that works exclusively on graphics. This frees up the computer's main processor for other tasks. A typical video card includes a graphics processing unit (GPU); a cooling mechanism (such as a fan); and memory and monitor ports such as HDMI.
AMD
AMD has had many brands throughout the years, such as Am2900, AMx86, Athlon, Sepron, Phenom and more. These brands, however, have been mostly phased out. The following brands are now being marketed. Ryzen Threadripper and Ryzen Mobile - As AMD's high-end CPU or desktop systems, they provide great processing speeds for gaming, 3D rendering, streaming, CAD, etc. Epyc - AMD's Epyc CPU was developed for high-end servers. It was introduced in June 2017, replacing the Opteron series of CPUs.
Active-Liquid Heat Sink
Active-liquid heat sink (ALHS) designs have become popular because they do not use external liquid pumps that are typically found in liquid cooling systems. An ALHS system is composed of a liquid heat sink, internal liquid pump, a fan, and a radiator that all actively pump cooled liquid in and out with no help from an outside pumping system. This space-saving design integrates the liquid heat sink and pump, eliminating the housing and reducing the overall dimensions of the cooling system. When ALHS is compared to liquid-cooled, heat pipe, and air-cooled systems, it consistently has the best thermal performance.
External Hard Disk Drives
An HDD that can be connected as a peripheral to a computer.
Audio Cards
An audio card (sound card) converts electrical signals to audio signals. This is done using a digital signal processor (DSP) chip. This specialized chip has been optimized for the operational needs of converting electrical signals to audio signals. The conversion recreates the sound we hear through computer speakers or earphones. Sound cards are also used for voice over IP (VoIP), teleconferencing, and other audio functions. Most audio cards use different kinds of input/output jacks and ports for connecting such things as headphones, microphones, or speakers. Audio cards have many uses, but are often used in configuring surround sound systems, such as a digital theater system used in a home theater.Surround systems are often referred to as 5.1 or 5.7 systems.The number (such as 5.1) refers to the number of speaker placements found in the system.
Thunderbolt
An interface primarily used on Apple computers that connects a monitor to a computer and can also provide DC power.
FireWire
An interface used to connect peripherals such as digital cameras and external hard drives to a computer. It is no longer commonly used.
Speakers
Another type of output is audio. Modern computing devices can send audio output to a set of speakers that can be integrated into the device itself or plugged into an external connector.On a desktop system, speakers can be connected using a USB cable, an audio jack, or a wireless connection. Some speakers can be configured using a stereo set up (right and left). More and more systems also support surround sound, where multiple speakers are arranged in various locations in a room giving you the feel of being in a cinematic environment.One of the more common surround sound systems is referred to as a 5.1 digital system, also known as Dolby Digital or Digital Theater System (DTS). These systems usually have two rear speakers (a left and a right), three front speakers (right, center, and left), and a subwoofer speaker for a deep bass sound. There is also a 7.1 system that includes two extra side speakers.To configure the audio settings in Windows 10, you can use the Settings app or Control Panel. Some of the settings include the speaker to use (internal or external), volume, etc.With the sound system installed and configured, you can easily adjust the sound using the speaker icon located in the Notification Area. Most laptops also include a function key that can be used to adjust the volume.
DisplayPort/Mini DisplayPort
DisplayPort connectors have 20 pins and come in two sizes: the standard DisplayPort and a smaller Mini DisplayPort. These interfaces are used to send high-quality, digital video and audio signals.DisplayPort and Mini DisplayPort function similarly to the HDMI. The main difference in appearance is that HDMI is beveled on two corners and DisplayPort is beveled on only one. DisplayPort has a greater bandwidth than HDMI. While HDMI supports a maximum bandwidth of 18 Gbps, DisplayPort 1.4 has a maximum bandwidth of 32.4 Gbps which supports a much greater resolution.Unlike HDMI, DisplayPort is royalty free (manufacturers do not have to pay a fee to use the interface). Because of this, DisplayPort has the potential to replace HDMI. DisplayPort uses a 20-pin connector. There is also a DisplayPort Dual-Mode (DP++). It allows DisplayPort sources to use simple passive adapters to connect to HDMI or DVI displays.
Electrical Engineer
Electrical engineers require extensive education and advanced technical knowledge. They oversee the design and development of computer devices and other systems that use electricity and electronics. Electrical engineers design tiny microchips as well as large and complex computer systems. Their duties include researching, designing, creating, and maintain these systems. As an electrical engineer, you would become proficient in using computer aided design or CAD software. You would also need to be comfortable collaborating with other engineers to create sophisticated computer devices and systems. Educational requirements for this type of job include a minimum of a Bachelor of Science degree in Electrical and Computer Engineering, Computer Science, Physics, or Mathematics, and frequently a master's degree in one of these fields.
External hard disk drives
External hard disk drives are frequently connected to computing devices to add additional storage capacity. For desktops and notebooks, the connection is usually a USB or a Thunderbolt connection. Mobile devices use a memory card that inserts into a memory card slot.External hard disk drives also typically come with an enclosure to protect the drive and provide access to the connection ports. Each of these connections provide faster bandwidth as follows: USB 2 - 480 Mbps, has a white or black colored inside. USB 3 - 5 Gbps, has a blue colored inside. USB 3.1 - 10 Gbps, has a blue colored inside. Thunderbolt 2 - 20 Gbps, uses the Mini DisplayPort (MiniDP) connector. Thunderbolt 3 - 40 Gbps, can connect multiple types of devices, such as video, high performance networks, and external storage. It uses the Universal Serial Bus (USB-C connector).
File systems
File systems use a special file called a directory file to keep track of the information in storage. The directory file: Contains the names of all the other files in the system. Keeps track of the file name, extension, creation date, read/write permissions, and location on the disk. When the user tells the computer to open a file, it looks at the directory and finds the appropriate location in storage to retrieve the file. Whenever a user adds, modifies, or deletes a file, the computer keeps track of the change in the directory file.The directory usually contains subdirectories (also called folders). Folders make the computer's file structure easier for humans to understand by grouping similar files into the same directory. For example, a person may make a folder for music, then subfolders for each band, then subfolders with the band folder for each album.This is called a hierarchical file system. The directory that contains all the subdirectories is called the root directory. Each file in a hierarchical system can be found at a specific location known as the file path.The backslash character (\) is often used in the file path to show the relationship between directories and the file. For example, a file with the file path C:\Users\Documents\picture.jpg is an image file. It is located in the Documents folder, which is in the Users folder. The Users folder is in the root directory (C:).
Flash storage
Flash storage uses special memory chips to store data. Flash storage drives are non-volatile. This means you can remove power from a flash storage device and its contents will remain intact. Flash storage devices can connect to computer systems in two ways. Using a USB port - This can be done using an external flash drive or a thumb drive. Using a card reader slot - These slots allow you to insert the flash storage into the device. Many computers and other devices (such as printers) come with a variety of slots in which a flash storage device can be inserted. For example, your system may have some or all of the following types of connectors: USB, CompactFlash, SmartMedia, MMC/SD.Once a flash storage device is connected and recognized by the operating system, you can store data on it and read data from it just as you would with a hard disk drive. Flash memory devices have the following advantages: They are portable. You can move a flash storage device from one system to another. In Windows, be sure to stop the device before unplugging it from the USB port or card reader. They are relatively fast. They can read and write information as fast as a standard hard disk drive. They provide a significant amount of storage capacity in a small physical package. They are great for laptops and mobile devices, because the device won't break if it gets bumped or shaken. Flash storage works well in many devices, including digital cameras, smart phones, digital camcorders, and tablets.
Drivers
For some peripheral devices, you may need to load drivers before connecting the device for the first time. Drivers contain software instructions that the computer needs in order to communicate with the device.For many devices, the necessary drivers are included with the operating system. Other devices may require you to manually install the drivers on the system prior to the first connection.Device drivers may also need to be updated when manufacturers fix bugs and vulnerabilities. If you need to uninstall a driver, the easiest and most effective method is to uninstall the original software package that was installed with the device.Sometimes, driver updates can cause new problems with your software. In this case, a very easy solution is to choose the Roll Back Driver option. This will revert the computer back to its state before installing the update.
Network
If a computer has access to a local network, either wired or wireless, you might install and configure peripherals to be accessed over the network. For example, you might install an Internet Protocol or IP-based printer and then configure it using a web page in a browser. Another example would be a Wi-Fi access point.
Immersion Cooling
Immersion cooling (IC) is an advanced system of cooling in which the coolant is in direct contact with the CPU. This type of cooling offers a high heat transfer that quickly reduces the temperature of the CPU's surface. Some IC technologies spray very fine droplets of de-ionized water directly onto the CPU, cooling the surface through a combination of thermal conduction and evaporation. Typically, the spray mechanism is activated only when the temperature of the CPU reaches a certain level. Immersion cooling can make changing computer components more complicated. For example, if you were to replace a memory module, you would have to pull out the tank and let the liquid drip out before you remove and replace the memory. This requires extra time and cleanup. Also, systems with IC cannot have any moving parts, such as spinning-disk hard drives.
Digital Projectors
In today's world there is often a need to project images from a computer to a larger output, such as a wall or screen. These are often used a team meeting or for training purposes. The devices used to do this are called digital projectors or video projectors.Depending on the need, these can be purchased as small portable devices or more expensive, larger ones are often mounted permanently on the ceiling or wall. These projectors can use LCD or CRT, but the better projectors use the digital light processing, which is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device.When used in conjunction with a computer, projectors can be connected to the computer using many of the same interfaces used by other devices, such as Thunderbolt, HDMI, VGA, and DVI.
Infrared
Infrared (IR) communication technology uses light waves to transmit information through the air. The light used by IR devices is just beyond the visible red light spectrum, so it's invisible to us.The simplest example of an IR device is a TV remote. When you press a button on a TV remote, IR light is emitted from the front of the remote and picked up by an IR receiver on the TV. Infrared is used by some portable devices such as tablets and smart phones.
Inkjet
Inkjet printers spray small dots of ink from an ink reservoir onto a sheet of paper. Inkjet printers can produce high-quality output and are relatively inexpensive to purchase. However, they have several disadvantages. Replacement ink cartridges are expensive. Ink cartridges have limited print capacities. The ink tends to bleed into the paper. Prints tend to fade over time. The ink will run if it gets wet, unless special water-resistant ink is used.
Intel
Intel has the following brands. Pentium 4 - Is Intel's brand for an entire series of single-core CPUs for desktops, laptops and entry-level servers. Pentium 4 CPUs were used from 2000 through 2008. Core - Intel's original 32-bit mobile dual-core x86 CPUs derived from the Intel P6 microarchitecture.Later the Core 2, 64-pit processor was released. It had multi-core support.Still later, Intel released three variants named Core i3, Core i5 and Core i7, but the names do not correspond to specific technical features like the number of cores.Intel divided the processors by their performance level, with i3 being low-level, i5 is mid-range, and i7 and i9 providing high-end performance. Celeron - Intel's brand for a number of low-end IA32 and x86-64 CPUs. Intel used the Celeron for many low-cost personal computers. Atom - Intel's IA-32 and x86-64 ultra-low-voltage microprocessors were designed to reduce electric consumption and power dissipation in comparison with other processors of the Intel Core series. The Atom CPU was used for devices, such as netbooks, nettops, smartphones, and tablets. Xeon - Intel's CPU was introduced in 1998 and is used primarily for non-consumer workstation, servers, and embedded system markets.
Laser
Laser printers use electrical charges and heat to fuse tiny plastic particles (called toner) to the paper. Laser printers have the following advantages over other types of printers: They produce higher-quality print output. They can print documents much faster. They are ideal for large volume print jobs. Replacement toner cartridges are more economical than inkjet cartridges. They are better suited for sharing over a network. The ink is waterproof and doesn't fade. The output doesn't bleed into the paper. Laser printers have the following disadvantages: They are more expensive to purchase. They are more difficult to maintain.
Gold
Midi/game port (a joystick).
Mini USB
Mini USB connectors are a smaller type of USB connector. They are commonly used for digital cameras and sometimes external hard drives. Cables with a Mini USB connector usually use a Type A connector on the other end of the cable to connect to the computer.
Audio
Most computers provide audio connectors. The pink connector is the microphone jack. It is used to connect a microphone to the system. The blue connector is the line-in connector. You can use it to connect an external audio source to the computer. The green connector is the line-out connector. It is used to connect speakers to the system.
Optical drive
Most desktop and notebook systems include an optical drive. Optical drives use light instead of magnetism to store information. They use microscopic light and dark spots on the bottom surface of the disc. There are three types of optical drives that can be installed in a computer. CD-ROM DVD Blu-ray Newer optical drives are backwards-compatible with older optical discs. For example, a DVD drive can also read CD-ROM discs. Likewise, a Blu-ray drive can also read DVD and CD-ROM discs. Optical discs have several advantages. Most optical discs can store a significant amount of data. Optical discs are portable. It's easy to take an optical disc out of one computer and move it to another. Optical discs also have several disadvantages. They are susceptible to damage. If the bottom of the disc gets scratched, the computer may not be able to read it. Optical discs come in both read-only and read-write formats.If a disc is read-only, you can read information from it, but you can't save information to it.Read-write optical discs do allow you to save information on them, but the process of writing information to one of these discs (called burning) can be quite slow.
x86 Processors
Most large computers, such as desktops, laptops, and servers, use x86 processors. x86 refers to the processor's instruction set which is the list of commands that a processor can execute. Today, most x86 CPUs are designed to process 64 bits of information at once. Older x86 processors could only process 32 bits at a time. The original x86 processors were designed for 16-bit instructions. The two biggest manufacturers of x86 processors are Intel and AMD. 64-bit x86 processors were originally referred to as x86-64 to distinguish them from the 32-bit x86 processors. This is now typically shortened to x64 for 64-bit and x86 for 32-bit processors. 64-bit computers are backwards compatible; they can run both 32-bit and 64-bit programs.
Cooling
One of the problems of high-speed computing is that it can produce a lot of heat. A typical desktop CPU can get hot enough to boil water. This much heat can damage delicate components if it isn't appropriately dealt with.In a typical desktop system, this is done with heat sinks and fans. A heat sink is a piece of metal that absorbs heat in a way that makes it easy to dissipate. Heat travels up the heat sink into thin branches, which maximize its contact with the air. Fans throughout the system replace the hot air inside the machine with cool air from the outside.
Scanner
Scanners can be connected to a computer to allow you to scan paper documents into digital files.Many newer scanners use both Optical Character Recognition (OCR) software to scan text documents into editable text files and Windows Image Acquisition (WIA) software to capture images.Scanners can be connected to desktops or laptops using a USB or FireWire connection.Wireless scanners are also available. There are many types of scanners, such as: Flatbed scanner - Provides a flat, glass surface on which you place the item to be scanned; similar to making a copy on a copy machine. It works as follows:White light, usually provided by a cold cathode florescent lamb (CCFL), shines on the object being scanned and creates the image by reading the intensity and color of light that is reflected from the object.The image is recorded using a charge-coupled device (CCD), which is an integrated circuit. The quality of the image is determined by the number of pixels per inch (ppi) that are captured.Most scanners let you determine how many pixels to use. Each pixel is a sample of an original image, therefore the more samples (pixels) being capture increases the quality of the image. Multi-function Devices - Multi-function devices (MFD) may provide for flatbed scanning, but may also (or instead of) provide a way to feed the document to be scanned using a sheet feeder.Some sheet feeders support only thinner paper, so check with the manufacture for the specific thickness supported.
FireWire
Some computers provide a FireWire connector. FireWire is an IEEE 1394 interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It's connectors are rectangular in shape with a bevel on one end to keep you from inserting them the wrong way.FireWire allows you to connect external devices, such as digital cameras, external hard drives, and scanners to the computer. A powered FireWire connector has 6 pins (FireWire 400 standard) and an unpowered one has 4 pins.The 400 standard has a transfer speed of up to 400 Mbps. FireWire can handle up to 63 units on the same bus, supports PnP, and is hot swappable. It was first developed by Apple.FireWire also has an IEEE 1394 interface standard; it is known as FireWire 800 and has 9 pins. It provides increased data transfer rates of up to 3200 Mbps using an optical cable or beta mode. Other FireWire standards include: FireWire S800T (IEEE-1394c) and FireWire S1600 and S3200.
Synthesized DNA Strands
Synthetically produced artificial DNA that is capable of storing vast amounts of information and may be a solution to long-term massive storage.
RAM
The CPU is great at performing calculations, but it can deal with only one line of instructions at a time. It can't keep track of the whole program all at once. Instead, the computer stores this information in random-access memory (RAM).When you run a program, the computer loads the instructions into its RAM. Then, the processor gets the first line of instructions from the RAM, executes it, and writes the result back into RAM to use later. This system bus path between the CPU and RAM is sometimes called the front side bus, (FSB).RAM is extremely fast, but it's also volatile. This means that if you turn the computer system off, everything in RAM is deleted or lost. For this reason, RAM is sometimes called short-term memory. It's only concerned with whatever the computer is working on at the time. RAM is added to a computer using a RAM stick, also known as a Dual In-line Memory Module (DIMM). The following is a list of the main types of RAM: DRAM - Commonly used as the main type of RAM in a computer. Key points are: DRAM uses a transistor and a capacitor within an integrated circuit. To store something in DRAM, a data bit is stored in the capacitor. Since capacitors leak small amounts of electricity, DRAM must be refreshed, meaning it is given a new electrical charge. SRAM - Also uses transistors, but unlike DRAM, SRAM stores its information in the transistor. Therefore, it does not need to be refreshed. Data stored in SRAM remains there until the power to the computer is turned off. SDRAM - SDRAM is synchronized DRAM. Key points are: The memory and CPU clock speed are synchronized. The synchronization .enables the memory controller to know the exact clock cycle when the data requested will be ready. SDRAM uses a 64-bit bus which means it can send 64 bits of information in each clock cycle. DDR SDRAM - DDR stands for Double Data Rate. Key points are: DDR transfers data twice as fast as SDRAM; once at the beginning a the clock cycle and again at the end of the clock cycle. DDR transfers 64-bits at a time. This process is also known as double-pumped. With each improvement to DDR, a new number was added to the name, such as DDR2, DDR3, and DDR4. DDR5 is soon to be released. With each new release, the way the memory works becomes faster and uses less power.
GPU
The CPU is the main processor in a computer. Often computers require additional processing power for creating images and graphics. This is supplied by a graphics processing unit (GPU). Most computers handle graphics processing through the CPU and RAM on the motherboard. This is called integrated graphics (on-board graphics).Computers used primarily for gaming, video editing, 3D modeling, and animation need a second GPU that's dedicated to graphics processing. The best dedicated graphics cards (often called video cards) are expensive because they also include their own specialized RAM and cooling fan.
DVI Video
The Digital Visual Interface (DVI) connector is designed to connect digital monitors to a computer, typically flat-panel. It is typically white with three rows of eight pins. There are multiple versions of DVI connectors, such as DVI-I (it integrates both digital and analog connections), DVI-D (digital connections only), and DVI-A (analog connections only).DVI-D and DVI-I come in either Single Link or Dual Link. Dual link supports higher resolutions. Single link cables can be identified as having 8 pins missing, while dual link cables use all 24 pins. Most computers now use HDMI, DisplayPort, or Thunderbolt instead of DVI.
HDMI
The High-Definition Multimedia Interface (HDMI) connector uses digital signals and is now available on a wide variety of devices such as computers, monitors, TVs, Blu-Ray players, etc. It requires a royalty to use. As the name implies, cables using an HDMI connector are used to transfer high-definition signals and supports both audio and video data.There have been several versions of HDMI; v2.1 is the latest. It offers faster bandwidth than previous versions.HDMI uses a 19 pin configuration for types A, C, and D. Type C is the Mini HDMI connector (often used for portable devices, such as DSLR cameras). Type D is smaller and is known as the Micro HDMI (often used on smaller portable devices such as smartphones).
Power Supply Unit
The PSU is mounted just inside the back of the computer's case. It can be found by following the power cable to the back of the computer. At the back of the power supply, you will see a fan that sends air out of the case. PSUs are rated by wattage to show how much power they can provide to the computer. Power requirements for a personal computer without high-performing CPUs or graphics cards is usually 300W to 500W. High-performance computers can use up to 1000W. Most modern desktop computer PSUs conform to the ATX specification that provides 5-Volt Standby (5VSB) voltage. ATX PSUs receive a signal from the motherboard to power the computer on or off and show when DC voltages are safe to power up and boot. The PSU has large, colorful bundles of wires which are designed to plug into the motherboard, fans, hard drives, and optical drives.
Thunderbolt
The Thunderbolt (TB) interface is compatible with DisplayPort and is primarily used on Apple computers. Thunderbolt ports can also provide DC power. They are mainly used for external displays, but they can also be used to connect other peripheral devices. There have been many version of this connector: Thunderbolt 1 - Developed around 2011. Thunderbolt 2 - Developed 2013 and supports up to 20 Gbps. Thunderbolt 3 - Developed by Intel and doubles the bandwidth to 40 Gbps. Maximum performance is for cable lengths over 0.5 meters (1.6 feet). Thunderbolt 4 - Key differences between 3 & 4 are: support for USB4, minimum bandwidth of 32 Gbps, and support for dual 4K displays.
USB Type C
The USB Type C specification was introduced in 2014. It is simpler than the previous types. Both ends of a Type C connector are the same and the cord allows bi-directional power flow, so a host device can charge a peripheral and a peripheral device can charge a host.Best of all, you don't need a specialized connector for each pair of devices. All ports are Type-C and one connector works for all ports, even Thunderbolt ports in newer devices. Since the end of the Type C cable is symmetrical, it can be plugged in facing up or down.
VGA Video
The Video Graphics Array (VGA) connector is designed for analog signals and has 15 pins. It is used to connect older or legacy monitors to a computer. You can identify this connector by its blue color and three rows of pins. VGA is not efficient at supporting high resolutions.There have been several versions of VGA standards over time, but all have used the same port and are generally backwards compatible. Most modern displays use the XGA standard described below: VGA:640 x 480 resolution16 colorsSVGA:800 x 600 resolution4- or 8-bit colorsXGA:1024 x 768 resolution32- bit colors
Mouse
The hardware within the mouse can keep track of its physical location on a hard surface. Using this information, it can determine how far you have moved the mouse and in what direction. This information is sent to the computer that moves the cursor on the screen accordingly.An external mouse can be connected to a desktop or laptop using a PS/2 port (for older systems), a USB port, or a wireless connection.Although the software (drivers) needed to use the mouse are typically installed by default, you can use the Windows Settings app or Control Panel to make changes to how the mouse functions. To configure a mouse, go to Mouse Properties from Control Panel/Settings. To change the speed of the double click in Windows, select the Activities tab. Then move the slider left to slow down the click speed and right to speed it up
Size limitations
The maximum file size a file system can support. This is a problem only for old file systems. For example FAT32 had a maximum file size of 4 gigabytes.Modern file systems have limitations that are so large it's impossible that a single file would ever approach the limit. The NTFS file system used by Windows, supports a maximum file size of 16 exabyte's. That's enough space to store every single YouTube video in a single file.
Hard disk drive
The most common type of long-term storage is the hard disk drive (HDD). Hard disks use thick, magnetic disks encased in a protective housing to store data. Because a hard disk drive is usually installed inside of a computer, it can be difficult to move between systems.If you need a portable hard disk, use an external hard disk drive that uses a USB or FireWire connection to the computer.Hard disks can store a large amount of data, but because they rely on moving parts, they're prone to failure if they get shaken or jostled too much. Hard disks have the following characteristics: Relatively inexpensive Fast Can hold a lot of information Hard disks can come in various sizes or what is called form factors. Key points about form factors include: Most desktop computers usually use a form factor of 3.5 inches. Most laptops use a 2.5 inch form factor. This measurement represents the approximated diameter of the platter encoded in the driver. The 3.5 HDD are usually faster, but due to their size won't fit in a laptop computer. The capacity of an HDD is ever increasing, from 100 GB up to 18TB. As technology continues to improve, these numbers are likely to increase. The performance of a HDD is determined by: How fast it can read and write data, measured in revolutions per minute (RPM). Latency (access time). Faster drives have higher RPMs and lower latency. For example, at the time this course was written, the Seagate 18TB Exos X18 functions at 7200 RPM with an average latency of 4.16ms (milliseconds).Hard disks are run by a controller. These controllers are sometimes built into the motherboard but are often a separate card in an expansion slot. The controller connects the physical HDD to the motherboard.Some of the most common HDD controllers are the small computer system interface (SCSI), the integrated drive electronics (IDE), the enhanced IDE (EIDE), the parallel advanced technology attachment (PATA), and the serial advanced technology attachment (SATA). SCSI - A SCSI (scuzzy) controller was one of the first disk controllers. It was developed in the 1970s. It has a 50-pin flat ribbon connector. SCSI controllers are now being phased out. IDE/EIDE/PATA - Controllers based on the IBM PC industry standard architecture (ISA) 16-bit bus standard. SATA - SATA supports disk hot-swapping. This means the drive can be changed while the computer is powered on. SATA uses better cables and provides faster speeds than SCSI and IDE/EIDE/PATA. SATA is the most common controller used in desktop and laptop computers. There are usually four SATA ports on most motherboards.
Monitor
The most common type of output device is the monitor. Information is usually displayed on a monitor screen as it's being processed by the computer. Laptop and mobile devices use an integrated screen, while most desktop systems use an external monitor connected to a video port.For desktop computers, the most common monitor is the flat-screen displays. Flat-screen displays/monitors are known as Liquid Crystal Display (LCD). While the old-styled cathode-ray tube (CRT) screens produced the image using electron guns, the flat-screen monitors use fluorescent or light emitting diode (LED) light to illuminate each pixel, each with the subpixels capable of generating the primary colors (red, green, and blue).Desktop and laptop computers can often support multiple monitors. This can be done if the existing graphic card supports multiple output devices, there are multiple graphic cards installed, or by using a display interface that lets you daisy-chain monitors, such as Thunderbolt or DisplayPorts.In Windows 10, the easiest way to configure multiple monitors is to right-click on the desktop and select Display Settings. This opens the Settings app to the Display page. When using multiple monitors, you have the choice to duplicate what is on one screen to the other screens or to extend the desktop to all of the monitors. This means that you can view different content on each display.When extending monitors it's important to place the monitors in the correct order in the Settings app so the mouse will move in a natural way from screen to screen. Each monitor can also be configured with its own resolution settings.
CPU
The most important part of any computer system is the central processing unit (CPU). Just like the brain controls the body, the CPU controls the other parts of the computer by getting information from them and then telling them what to do. A CPU is a programmable integrated circuit (PIC) or also known as a microprocessor. Microprocessors, such as the CPU, contain a set of electronic circuits created on a small flat piece of semiconductor material, normally made of silicon. After receiving raw input data from the user, the CPU applies the data to a list of instructions, called a computer program. The CPU then follows (executes) each line of the computer program in order, turning the data from the user into information. This is called processing. CPUs have a clock speed, sometimes call a clock rate. A computer's CPU clock speed is one indication of its performance capabilities. The CPU clock speed is a representation of how may cycles (number of instructions) per second it can execute, rated in gigahertz (GHz).
Power Supply
The motherboard makes sure sure all components get the right amount of electricity. This electricity comes to the computer through a power supply unit.Power supplies take AC power from the wall outlet and convert it into DC power. They typically have a variety of cables and plugs that attach to the motherboard near each powered component.
Encryption
The process of converting information so that it cannot be understood without a key to convert it back (de-encrypt it). Encryption is used to prevent unauthorized access.By encrypting files containing sensitive information, the computer prevents unauthorized people from accessing sensitive information stored on the computer.
Partitioning
The process of dividing a single physical disk into multiple logical drives called volumes.
Journaling
The process of noting in a change log every time a file changes. Journaling helps prevent data loss in the case of a power outage or other system malfunction.
Journaling
The process of tracking changes to a file so that a file can be repaired or restored in case of file corruption or data loss.
File
The smallest container within a computer's storage system that is used to store information such as data, settings, and commands used in a computer program. A file is the smallest container that can be copied, deleted, or moved within a file system.
File Permissions
The use of user and file attributes that control which users can read, write, move, or delete each file.
File extensions
There are many file types. Developers can make new ones whenever they need to. To determine a file's type, you can look at the filename.In Windows, a filename has two parts, the name of the file and the file extension. The two parts are separated by a period. For example: Image extensions include .jpg, .gif, and .png. Audio file types include .mp3, .wav, and .wma. Video file types include .mp4, .avi, and .wmv. Executable files run programs. They have their own extensions. The extensions differ by operating system type: Windows uses file extensions such as .com or .exe. Javescript uses .js. Linux uses .run. macOS uses .app. While executable file types exist for Linux, macOS, and Android, these platforms do not require file extensions for executable files. Windows requires executables to have a file extension.
Specific file systems
There are several different file systems a computer can use. They generally do the same thing as far as the user is concerned but work differently behind the scenes. File systems used by operating systems include: Older versions of Windows used a system called File Allocation Table 32-bit (FAT32). Modern Windows systems use New Technology File System (NTFS). Most older macOS systems use the extended Hierarchical File System (HFS+). However, starting with macOS 10.13 and later, Mac computers use the Apple File System (APFS). Linux distributions use the ext file system. Variations of ext include:The ext3 file system is a 64-bit file system that supports journaling. Journaling helps to prevent data loss from crashes, data corruption, and sudden power loss.The ext4 file system is currently used by most Linux systems. It has newer features that help to reduce file fragmentation; allows for larger volumes and files; and uses delayed allocation to improve flash memory life.B-Tree File System (BtrFS) is the file system that Linux is moving toward. It offers new features, such as transparent compression, drive pooling, online defragmentation, and on the fly snapshots.
Touch Screen
Touch screens are commonly used by mobile devices. A touch screen uses a special material overlaid on the top of the device's regular screen that can detect when you have touched it and where. As with a mouse, you can use touch screens to send data and commands to the device.Touch screen devices can also use a pen (sometimes called a stylus) to draw, tap, and select items on the screen. If you have the correct software, Windows can convert your handwriting into characters that can be used by other programs, such as a word processor.To configure the pen settings, open the Settings app and go to Devices > Pen & Windows Ink. A similar option is also available in Control Panel.
3D Flash Memory
Type of memory that implements tiers of solid-state flash memory stacked on top of each other allowing for much greater storage capacity at a lower cost than 2D flash memory.
USB Type B
USB Type B connectors have a square shape with a bevel on one edge to keep them from being plugged in the wrong way. They are designed for devices that are usually left plugged in for long periods of time, such as: Printers Scanners USB hubs Cables with a USB Type B connector typically use a Type A connector on the other end of the cable to connect to the computer.
USB
USB devices are hot-swappable. This means you can plug and unplug USB peripherals while the system is running. The system will automatically detect the addition or removal of a device and make the necessary configuration changes.To prevent data corruption when disconnecting external storage devices, you must stop them properly in the operating system before removing them. USB devices can be plugged in directly to a USB port on the computer or to an external USB hub that's connected to the computer.
Self-powered USB devices
USB ports can provide power over the connection. USB devices can receive up to 500 milliamps of power from a USB 2.0 port and up to 900 milliamps of power from a USB 3.0 port. If a device can operate on this much power, it's considered a bus-powered device. This means the USB port provides 100 percent of its power.If a device needs more power than this, it's considered a self-powered device and will typically have an external power adapter that plugs into a wall outlet.USB 2.0 ports can provide 2.5W of power. A standard USB 3.0 port can provide 4.5W of power and allows data transfer. A USB 3.0 dedicated charging port can provide 7.5W of power for a single device, but does not allow data transfer.
Bus Technology
When working with computes, a bus is the communication system that allows data to be transferred between the components inside a computer. The term bus comes from the Latin word omnibus, which means "for all". For example, a motherboard has many small wires spanning the motherboard. These tiny wires, or circuitry, make up the bus which as been imprinted on the circuit board, or PCB.
File formats
While it's possible for a file's data to be completely arbitrary, most files are organized in a specific way, called a file format. Using an image file as an example, files work in the following way: Files are organized by metadata and pixel data. The metadata store the total file size, the height and width of the image, the color depth, and other info the computer needs to process the file. The rest of the bytes in the file store the actual pixels that make up the image. When you tell a computer to open an image file, it looks at the metadata, then uses the information there to decode the file and show the picture.
Camera lens
A camera component that focuses the light that enters it into a point. Behind the point, the light spreads out again, eventually creating an upside-down image of the light that entered.
Infrared
A communication technology that uses light waves to transmit information through the air.
Registered Jack 45 (RJ-45) connector
A connector used to connect a computer to a wired network.
Scanner
A device that scans paper documents and converts them into digital files.
Solid State Devices (SSD)
A device with similar capacity to an HDD that uses flash storage instead of magnetic disks to store data. SSDs are much faster and more durable than hard disk drives but usually are more expensive.
Air Cooling
Air cooling is currently the most common method of cooling. By integrating fans in series (placed on top of one another) or in parallel configurations (side by side), they are able to efficiently move hot air out of the system. Air cooling doesn't require piping elements, tubing, or cables and is typically a cheaper option. Traditional air cooling does come with a few downsides, however. Fans that are used for cooling are not as efficient as other cooling technologies such as water cooling. Also, fans are often large and loud.
Micro USB
Micro USB connectors are the smallest type of USB connector. They are commonly used for connections to mobile devices, such as tablets and phones. Cables with a Micro USB connector generally use a Type A connector on the other end of the cable to connect to the computer.
PCI Express
PCI Express, or PCIe is a next generation I/O bus architecture. Rather than a shared bus, each PCIe slot links to a switch which prioritizes and routes data through a point-to-point dedicated connection and provides a serial full-duplex method of transmission.
Motherboard
The CPU and RAM are connected by a large flat component called a motherboard (sometimes called a system board). The motherboard is found in devices, such as laptops, desktops, and servers.The motherboard is like the spine in your body. It connects all the other parts to each other and sends electrical signals between them. For example, a motherboard gives you access to the input/output ports you use on the computer. These ports can include USB, HDMI, DVI, SATA (used for hard drives), RJ-45 (Ethernet), and audio.A major component of the motherboard is its built-in processors. Key points are: The built-in processors are also know as a chipset. They act as a communication hub or traffic control center for the motherboard. The chipset controls the compatibility of the components that can plug into the motherboard, including the CPU. The chipset provides function needed to run the computer. Without the chipset, the computer would require an adapter card to perform the function. Another important part of the motherboard is a chip that contains the Basic Input Output System (BIOS). When you start a computer, the BIOS makes sure all the necessary parts are plugged in and working properly. It then tells the operating system to start loading.
ARM Processors
The x86 processors are extremely powerful, but they consume a lot of power and generate immense heat. That's a problem for mobile devices, which depend on battery power and are often carried in their owners' pockets.Most tablets and smartphones use Advanced RISC Machine (ARM) processors. ARM processors use a reduced instruction set. This means they can't do as many types of things as x86 processors. The tradeoff is that they are smaller, consume less power, and generate less heat.These processors are used in many mobile devices and phones made by Apple, HTC, Nokia, Xiaomi, Sony Ericsson, Samsung, nVIDIA Tegra, and others.
NIC
Today, most computers need to connect to the internet. That's the job of the network interface card (NIC). Some motherboards have a NIC built in, while others need one to be added on. Some NICs are for a wired connection, some are for wireless, and some can do both.
Heat-Assisted Magnetic Recording
Type of drive that allows bits of data to become smaller and more tightly packed together while still retaining data. It uses a tiny laser to briefly heat the recording surface of the hard drive to write the data making it more receptive to the effects of magnetism, which allow writing on much smaller areas than were possible before.