praj-17/QA-MCQ-Open-ended huggingface dataset:
Title: USB
Context: By design, it is difficult to insert a USB plug into its receptacle incorrectly. The USB specification states that the required USB icon must be embossed on the "topside" of the USB plug, which "...provides easy user recognition and facilitates alignment during the mating process." The specification also shows that the "recommended" "Manufacturer's logo" ("engraved" on the diagram but not specified in the text) is on the opposite side of the USB icon. The specification further states, "The USB Icon is also located adjacent to each receptacle. Receptacles should be oriented to allow the icon on the plug to be visible during the mating process." However, the specification does not consider the height of the device compared to the eye level height of the user, so the side of the cable that is "visible" when mated to a computer on a desk can depend on whether the user is standing or kneeling.

question: What is difficult to do with a USB plug? 

answer: to insert a USB plug into its receptacle incorrectly

question: The USB specification states that the required USB icon must be what? 

answer: embossed on the "topside" of the USB plug

question: How is the USB icon located to each receptacle? 

answer: adjacent

question: Receptacles should be oriented to allow the icon on the plug to what? 

answer: to be visible during the mating process
Title: USB
Context: The standard connectors were deliberately intended to enforce the directed topology of a USB network: Type-A receptacles on host devices that supply power and Type-B receptacles on target devices that draw power. This prevents users from accidentally connecting two USB power supplies to each other, which could lead to short circuits and dangerously high currents, circuit failures, or even fire. USB does not support cyclic networks and the standard connectors from incompatible USB devices are themselves incompatible.

question: What do Type-A receptacles do on host devices? 

answer: supply power

question: What do Type-b receptacles do on target devices? 

answer: draw power

question: What do the receptacles prevent user from doing? 

answer: from accidentally connecting two USB power supplies to each other

question: What networks do USB not support? 

answer: cyclic networks
Title: USB
Context: The standard connectors were designed to be robust. Because USB is hot-pluggable, the connectors would be used more frequently, and perhaps with less care, than other connectors. Many previous connector designs were fragile, specifying embedded component pins or other delicate parts that were vulnerable to bending or breaking. The electrical contacts in a USB connector are protected by an adjacent plastic tongue, and the entire connecting assembly is usually protected by an enclosing metal sheath.

question: Standard connectors were designed to be what? 

answer: robust

question: Why were standard connectors designed to be so robust? 

answer: the connectors would be used more frequently

question: What as a drawback of previous connectors? 

answer: Many previous connector designs were fragile

question: How are the electrical contents of a USB connector protected? 

answer: by an adjacent plastic tongue

question: How is the entire connecting assembly of a USB connector protected? 

answer: by an enclosing metal sheath
Title: USB
Context: The connector construction always ensures that the external sheath on the plug makes contact with its counterpart in the receptacle before any of the four connectors within make electrical contact. The external metallic sheath is typically connected to system ground, thus dissipating damaging static charges. This enclosure design also provides a degree of protection from electromagnetic interference to the USB signal while it travels through the mated connector pair (the only location when the otherwise twisted data pair travels in parallel). In addition, because of the required sizes of the power and common connections, they are made after the system ground but before the data connections. This type of staged make-break timing allows for electrically safe hot-swapping.

question: Where is the external metallic sheet connected? 

answer: typically connected to system ground

question: What provides a degree of protection from interference with the USB signal? 

answer: This enclosure design

question: This type of stage make-break timing allows for what? 

answer: electrically safe hot-swapping.
Title: USB
Context: The newer micro-USB receptacles are designed for a minimum rated lifetime of 10,000 cycles of insertion and removal between the receptacle and plug, compared to 1,500 for the standard USB and 5,000 for the mini-USB receptacle. Features intended to accomplish include, a locking device was added and the leaf-spring was moved from the jack to the plug, so that the most-stressed part is on the cable side of the connection. This change was made so that the connector on the less expensive cable would bear the most wear instead of the more expensive micro-USB device. However the idea that these changes did in fact make the connector more durable in real world use has been widely disputed, with many contending that they are in fact, much less durable.

question: What are the newer micro-USB receptacles designed for? 

answer: a minimum rated lifetime of 10,000 cycles of insertion

question: What is the minimum rated lifetime for the standard USB receptacle? 

answer: 1,500

question: After a leaf-spring was moved from jack to the plug, the most stressed part was found where? 

answer: on the cable side of the connection

question: Why was the change made for the USB device? 

answer: so that the connector on the less expensive cable would bear the most wear
Title: USB
Context: The USB standard specifies relatively loose tolerances for compliant USB connectors to minimize physical incompatibilities in connectors from different vendors. To address a weakness present in some other connector standards, the USB specification also defines limits to the size of a connecting device in the area around its plug. This was done to prevent a device from blocking adjacent ports due to the size of the cable strain relief mechanism (usually molding integral with the cable outer insulation) at the connector. Compliant devices must either fit within the size restrictions or support a compliant extension cable that does.

question: What type of tolerances does the USB standard specify for compliant USB connectors? 

answer: loose tolerances

question: Why were loose tolerances allowed for compliant USB connectors? 

answer: to minimize physical incompatibilities in connectors from different vendors

question: How is a weakness addressed in some other connector standards? 

answer: the USB specification also defines limits to the size of a connecting device

question: Due to size restrictions compliant devices must what? 

answer: fit within the size restrictions or support a compliant extension cable that does
Title: USB
Context: In general, USB cables have only plugs on their ends, while hosts and devices have only receptacles. Hosts almost universally have Type-A receptacles, while devices have one or another Type-B variety. Type-A plugs mate only with Type-A receptacles, and the same applies to their Type-B counterparts; they are deliberately physically incompatible. However, an extension to the USB standard specification called USB On-The-Go (OTG) allows a single port to act as either a host or a device, which is selectable by the end of the cable that plugs into the receptacle on the OTG-enabled unit. Even after the cable is hooked up and the units are communicating, the two units may "swap" ends under program control. This capability is meant for units such as PDAs in which the USB link might connect to a PC's host port as a device in one instance, yet connect as a host itself to a keyboard and mouse device in another instance.

question: USB cables and device have only what on their ends? 

answer: plugs

question: Hosts and devices only have what in terms of connecting to a USB device? 

answer: receptacles

question: Devices usually have what type of receptacle? 

answer: one or another Type-B variety

question: Hosts almost always have what type of receptacle? 

answer: Type-A receptacles
Title: USB
Context: Various connectors have been used for smaller devices such as digital cameras, smartphones, and tablet computers. These include the now-deprecated (i.e. de-certified but standardized) mini-A and mini-AB connectors; mini-B connectors are still supported, but are not OTG-compliant (On The Go, used in mobile devices). The mini-B USB connector was standard for transferring data to and from the early smartphones and PDAs. Both mini-A and mini-B plugs are approximately 3 by 7 mm; the mini-A connector and the mini-AB receptacle connector were deprecated on 23 May 2007.

question: What has been used to connect digital cameras. smartphones and other devices to tablet computers? 

answer: Various connectors

question: What was standard for transferring data to and from the earlier type of smartphones? 

answer: The mini-B USB connector

question: How large are both mini-A and mini-B plugs? 

answer: approximately 3 by 7 mm

question: When were the mini-A connector and and the mini-AB receptacle connector depreceated? 

answer: 23 May 2007
Title: USB
Context: The micro plug design is rated for at least 10,000 connect-disconnect cycles, which is more than the mini plug design. The micro connector is also designed to reduce the mechanical wear on the device; instead the easier-to-replace cable is designed to bear the mechanical wear of connection and disconnection. The Universal Serial Bus Micro-USB Cables and Connectors Specification details the mechanical characteristics of micro-A plugs, micro-AB receptacles (which accept both micro-A and micro-B plugs), and micro-B plugs and receptacles, along with a standard-A receptacle to micro-A plug adapter.

question: What is the micro connector designed for? 

answer: to reduce the mechanical wear on the device

question: What is the easier-to-replace cable designed for? 

answer: to bear the mechanical wear of connection and disconnection

question: What is the micro-plug rated for? 

answer: 10,000 connect-disconnect cycles
Title: USB
Context: The cellular phone carrier group Open Mobile Terminal Platform (OMTP) in 2007 endorsed micro-USB as the standard connector for data and power on mobile devices In addition, on 22 October 2009 the International Telecommunication Union (ITU) has also announced that it had embraced micro-USB as the Universal Charging Solution its "energy-efficient one-charger-fits-all new mobile phone solution," and added: "Based on the Micro-USB interface, UCS chargers also include a 4-star or higher efficiency rating—​​up to three times more energy-efficient than an unrated charger."

question: In 2007 who endorsed micro-USB as the standard connector for data and power on mobile devices? 

answer: The cellular phone carrier group Open Mobile Terminal Platform

question: When did the ITU announce that it had embraced micro-USB as the Universal Charging Solution? 

answer: 22 October 2009

question: What has energy-efficient one-charger-fits-all new mobile phone solution? 

answer: micro-USB
Title: USB
Context: The European Standardisation Bodies CEN, CENELEC and ETSI (independent of the OMTP/GSMA proposal) defined a common External Power Supply (EPS) for use with smartphones sold in the EU based on micro-USB. 14 of the world's largest mobile phone manufacturers signed the EU's common EPS Memorandum of Understanding (MoU). Apple, one of the original MoU signers, makes micro-USB adapters available – as permitted in the Common EPS MoU – for its iPhones equipped with Apple's proprietary 30-pin dock connector or (later) Lightning connector.

question: Who defined a common External Power Supply for use with smartphones sold? 

answer: The European Standardisation Bodies CEN, CENELEC and ETSI

question: How many mobile phone manufacturers signed the EU's common EPS (MoU)? 

answer: 14

question: Who was one of the original MoU signers? 

answer: Apple
Title: USB
Context: All current USB On-The-Go (OTG) devices are required to have one, and only one, USB connector: a micro-AB receptacle. Non-OTG compliant devices are not allowed to use the micro-AB receptacle, due to power supply shorting hazards on the VBUS line. The micro-AB receptacle is capable of accepting both micro-A and micro-B plugs, attached to any of the legal cables and adapters as defined in revision 1.01 of the micro-USB specification. Prior to the development of micro-USB, USB On-The-Go devices were required to use mini-AB receptacles to perform the equivalent job.

question: What are all USB On-The-Go devices required to have? 

answer: one, and only one, USB connector

question: Non-OTG compliant devices are not allowed to use what? 

answer: the micro-AB receptacle

question: Why are the Non-OTG compliant devices not allowed to use the micro-AB receptacle? 

answer: power supply shorting hazards on the VBUS line
Title: USB
Context: The OTG device with the A-plug inserted is called the A-device and is responsible for powering the USB interface when required and by default assumes the role of host. The OTG device with the B-plug inserted is called the B-device and by default assumes the role of peripheral. An OTG device with no plug inserted defaults to acting as a B-device. If an application on the B-device requires the role of host, then the Host Negotiation Protocol (HNP) is used to temporarily transfer the host role to the B-device.

question: The OTG device with the B-plug inserted is called what? 

answer: B-device

question: What does an OTG device default to with no plug inserted? 

answer: to acting as a B-device

question: What is the A-device responsible for? 

answer: powering the USB interface when required
Title: USB
Context: USB is a serial bus, using four shielded wires for the USB 2.0 variant: two for power (VBUS and GND), and two for differential data signals (labelled as D+ and D− in pinouts). Non-Return-to-Zero Inverted (NRZI) encoding scheme is used for transferring data, with a sync field to synchronize the host and receiver clocks. D+ and D− signals are transmitted on a twisted pair, providing half-duplex data transfers for USB 2.0. Mini and micro connectors have their GND connections moved from pin #4 to pin #5, while their pin #4 serves as an ID pin for the On-The-Go host/client identification.

question: What is USB? 

answer: a serial bus

question: What kind of wires does the USB 2.0 variant use? 

answer: four shielded wires

question: What are the four shielded wires in the USB 2.0 variant used for? 

answer: two for power (VBUS and GND), and two for differential data signals
Title: USB
Context: USB 2.0 provides for a maximum cable length of 5 meters for devices running at Hi Speed (480 Mbit/s). The primary reason for this limit is the maximum allowed round-trip delay of about 1.5 μs. If USB host commands are unanswered by the USB device within the allowed time, the host considers the command lost. When adding USB device response time, delays from the maximum number of hubs added to the delays from connecting cables, the maximum acceptable delay per cable amounts to 26 ns. The USB 2.0 specification requires that cable delay be less than 5.2 ns per meter (192 000 km/s, which is close to the maximum achievable transmission speed for standard copper wire).

question: How long is the maximum cable length the USB 2.0 provides? 

answer: 5 meters for devices running at Hi Speed

question: What is the maximum acceptable delay per cable? 

answer: 26 ns

question: What does theUSB 2.0 specification require? 

answer: cable delay be less than 5.2 ns per meter
Title: USB
Context: A unit load is defined as 100 mA in USB 1.x and 2.0, and 150 mA in USB 3.0. A device may draw a maximum of five unit loads from a port in USB 1.x and 2.0 (500 mA), or six unit loads in USB 3.0 (900 mA). There are two types of devices: low-power and high-power. A low-power device (such as a USB HID) draws at most one-unit load, with minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0. A high-power device draws, at most, the maximum number of unit loads the standard permits. Every device functions initially as low-power (including high-power functions during their low-power enumeration phases), but may request high-power, and get it if available on the providing bus.

question: What is a unit load defined as? 

answer: 100 mA in USB 1.x and 2.0

question: How much is a unit load in USB 3.0? 

answer: 150 mA

question: What is the maximum amount of load a USB 1. and 2.0 device may draw? 

answer: five unit loads

question: What is the maximum amount of load a USB 3.0 device may draw? 

answer: six unit loads
Title: USB
Context: Some devices, such as high-speed external disk drives, require more than 500 mA of current and therefore may have power issues if powered from just one USB 2.0 port: erratic function, failure to function, or overloading/damaging the port. Such devices may come with an external power source or a Y-shaped cable that has two USB connectors (one for power and data, the other for power only) to plug into a computer. With such a cable, a device can draw power from two USB ports simultaneously. However, USB compliance specification states that "use of a 'Y' cable (a cable with two A-plugs) is prohibited on any USB peripheral", meaning that "if a USB peripheral requires more power than allowed by the USB specification to which it is designed, then it must be self-powered."

question: What is an example of a device that requires more than 500 mA of current? 

answer: high-speed external disk drives

question: What is an issue that may occur if a high-speed external disk drive is powered from just one USB 2.0 port. 

answer: may have power issues

question: What does USB compliance specification prohibit? 

answer: "use of a 'Y' cable (a cable with two A-plugs)
Title: USB
Context: The USB Battery Charging Specification Revision 1.1 (released in 2007) defines a new type of USB port, called the charging port. Contrary to the standard downstream port, for which current draw by a connected portable device can exceed 100 mA only after digital negotiation with the host or hub, a charging port can supply currents between 500 mA and 1.5 A without the digital negotiation. A charging port supplies up to 500 mA at 5 V, up to the rated current at 3.6 V or more, and drops its output voltage if the portable device attempts to draw more than the rated current. The charger port may shut down if the load is too high.

question: What defines a new type of USB port, called the charging port? 

answer: The USB Battery Charging Specification Revision 1.1

question: When was the USB Battery Charging Specification Revision 1.1 released? 

answer: in 2007

question: What was the USB Battery Charging Specification Revision 1.1 called? 

answer: the charging port

question: What does a charging port supply? 

answer: up to 500 mA at 5 V
Title: USB
Context: Two types of charging port exist: the charging downstream port (CDP), supporting data transfers as well, and the dedicated charging port (DCP), without data support. A portable device can recognize the type of USB port; on a dedicated charging port, the D+ and D− pins are shorted with a resistance not exceeding 200 ohms, while charging downstream ports provide additional detection logic so their presence can be determined by attached devices. (see ref pg. 2, Section 1.4.5, & Table 5-3 "Resistances"—pg. 29).

question: How many types of charging ports exist? 

answer: Two types

question: What can a portable device recognize? 

answer: the type of USB port

question: What are the D+ and D- shortened with? 

answer: a resistance not exceeding 200 ohms
Title: USB
Context: The USB Battery Charging Specification Revision 1.2 (released in 2010) makes clear that there are safety limits to the rated current at 5 A coming from USB 2.0. On the other hand, several changes are made and limits are increasing including allowing 1.5 A on charging downstream ports for unconfigured devices, allowing high speed communication while having a current up to 1.5 A, and allowing a maximum current of 5 A. Also, revision 1.2 removes support for USB ports type detection via resistive detection mechanisms.

question: What does the USB Battery Charging Specification Revision 1.2 make clear of? 

answer: there are safety limits to the rated current at 5 A coming from USB 2.0

question: What does revision 1.2 remove? 

answer: USB ports type detection via resistive detection mechanisms

question: When was USB Battery Charging Specification Revision 1.2 released? 

answer: in 2010
Title: USB
Context: In July 2012, the USB Promoters Group announced the finalization of the USB Power Delivery ("PD") specification, an extension that specifies using certified "PD aware" USB cables with standard USB Type-A and Type-B connectors to deliver increased power (more than 7.5 W) to devices with larger power demand. Devices can request higher currents and supply voltages from compliant hosts –  up to 2 A at 5 V (for a power consumption of up to 10 W), and optionally up to 3 A or 5 A at either 12 V (36 W or 60 W) or 20 V (60 W or 100 W). In all cases, both host-to-device and device-to-host configurations are supported.

question: When did the USB Promoters Group announce the finalization of the USB Power Delivery specification? 

answer: In July 2012

question: What can devices request? 

answer: higher currents and supply voltages from compliant hosts

question: In all cases, both host-to-device and device-to-host configurations are what? 

answer: supported
Title: USB
Context: The USB Power Delivery revision 2.0 specification has been released as part of the USB 3.1 suite. It covers the Type-C cable and connector with four power/ground pairs and a separate configuration channel, which now hosts a DC coupled low-frequency BMC-coded data channel that reduces the possibilities for RF interference. Power Delivery protocols have been updated to facilitate Type-C features such as cable ID function, Alternate Mode negotiation, increased VBUS currents, and VCONN-powered accessories.

question: The USB Power Delivery revision 2.0 specification has been released as part of what? 

answer: USB 3.1

question: What does the USB Power Delivery revision 2.0 specification cover? 

answer: Type-C cable and connector with four power/ground pairs and a separate configuration channel

question: Power delivery protocols have been updated to facilitate what? 

answer: Type-C features
Title: USB
Context: Sleep-and-charge USB ports can be used to charge electronic devices even when the computer is switched off. Normally, when a computer is powered off the USB ports are powered down, preventing phones and other devices from charging. Sleep-and-charge USB ports remain powered even when the computer is off. On laptops, charging devices from the USB port when it is not being powered from AC drains the laptop battery faster; most laptops have a facility to stop charging if their own battery charge level gets too low.

question: What can sleep-and-charge USB ports be used to do? 

answer: charge electronic devices even when the computer is switched off

question: What is normally powered off whenever the computer is off? 

answer: USB ports

question: What remain powered even whenever the computer is powered off? 

answer: Sleep-and-charge USB ports