sentence-transformers/squad huggingface dataset:
Passage: 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?

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

Question: Power delivery protocols have been updated to facilitate what?
Passage: 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?

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

Question: What remain powered even whenever the computer is powered off?
Passage: On Dell and Toshiba laptops, the port is marked with the standard USB symbol with an added lightning bolt icon on the right side. Dell calls this feature PowerShare, while Toshiba calls it USB Sleep-and-Charge. On Acer Inc. and Packard Bell laptops, sleep-and-charge USB ports are marked with a non-standard symbol (the letters USB over a drawing of a battery); the feature is simply called Power-off USB. On some laptops such as Dell and Apple MacBook models, it is possible to plug a device in, close the laptop (putting it into sleep mode) and have the device continue to charge.[citation needed]

Question: On what laptops are the USB ports marked with a USB symbol with an added lightening bolt icon?

Question: What does dell call the feature that lets USB drives to remain powered when the computer is off?

Question: On what laptops are the sleep-and-charge marked with a non-standard symbol?
Passage: The GSM Association (GSMA) followed suit on 17 February 2009, and on 22 April 2009, this was further endorsed by the CTIA – The Wireless Association, with the International Telecommunication Union (ITU) announcing on 22 October 2009 that it had also embraced the Universal Charging Solution as its "energy-efficient one-charger-fits-all new mobile phone solution," and added: "Based on the Micro-USB interface, UCS chargers will also include a 4-star or higher efficiency rating—up to three times more energy-efficient than an unrated charger."

Question: When did the GSM Association follow suit?

Question: UCS chargers will also include what?

Question: When was this further endorsed by the CTIA?
Passage: In June 2009, many of the world's largest mobile phone manufacturers signed an EC-sponsored Memorandum of Understanding (MoU), agreeing to make most data-enabled mobile phones marketed in the European Union compatible with a common External Power Supply (EPS). The EU's common EPS specification (EN 62684:2010) references the USB Battery Charging standard and is similar to the GSMA/OMTP and Chinese charging solutions. In January 2011, the International Electrotechnical Commission (IEC) released its version of the (EU's) common EPS standard as IEC 62684:2011.

Question: When did many of the largest mobile phone manufacturers sign an EC-sponsored MoU?

Question: What did the MoU make the manufacturers agree to do?

Question: When did the IEC release its version of the common EPS standard as IEC 62684:2011?
Passage: Some USB devices require more power than is permitted by the specifications for a single port. This is common for external hard and optical disc drives, and generally for devices with motors or lamps. Such devices can use an external power supply, which is allowed by the standard, or use a dual-input USB cable, one input of which is used for power and data transfer, the other solely for power, which makes the device a non-standard USB device. Some USB ports and external hubs can, in practice, supply more power to USB devices than required by the specification but a standard-compliant device may not depend on this.

Question: Some USB devices require what?

Question: Some devices such as an external hard and optical disk drive can use what?

Question: What is another alternative for power for an external hard and optical disk drive?

Question: What is the purpose of a dual-input USB cable?
Passage: In addition to limiting the total average power used by the device, the USB specification limits the inrush current (i.e., that used to charge decoupling and filter capacitors) when the device is first connected. Otherwise, connecting a device could cause problems with the host's internal power. USB devices are also required to automatically enter ultra low-power suspend mode when the USB host is suspended. Nevertheless, many USB host interfaces do not cut off the power supply to USB devices when they are suspended.

Question: What does the USB specification limit?

Question: When is the inrush current affected by the USB specification?

Question: What are USB devices required to enter?

Question: Many USB host interfaces do not what?
Passage: Some non-standard USB devices use the 5 V power supply without participating in a proper USB network, which negotiates power draw with the host interface. These are usually called USB decorations.[citation needed] Examples include USB-powered keyboard lights, fans, mug coolers and heaters, battery chargers, miniature vacuum cleaners, and even miniature lava lamps. In most cases, these items contain no digital circuitry, and thus are not standard compliant USB devices. This may cause problems with some computers, such as drawing too much current and damaging circuitry. Prior to the Battery Charging Specification, the USB specification required that devices connect in a low-power mode (100 mA maximum) and communicate their current requirements to the host, which then permits the device to switch into high-power mode.

Question: What do some non-standard USB devices use?

Question: What Negotiates power draw with the host interface?

Question: What does the USB specification require prior to the Battery Charging Specification?
Passage: USB data is transmitted by toggling the data lines between the J state and the opposite K state. USB encodes data using the NRZI line coding; a 0 bit is transmitted by toggling the data lines from J to K or vice versa, while a 1 bit is transmitted by leaving the data lines as-is. To ensure a minimum density of signal transitions remains in the bitstream, USB uses bit stuffing; an extra 0 bit is inserted into the data stream after any appearance of six consecutive 1 bits. Seven consecutive received 1 bits is always an error. USB 3.0 has introduced additional data transmission encodings.

Question: How is the USB data transmitted?

Question: What does USB use to encode data?

Question: To ensure a minimum density of signal transitions remains in the bitsream, what does USB use?
Passage: A USB packet's end, called EOP (end-of-packet), is indicated by the transmitter driving 2 bit times of SE0 (D+ and D− both below max.) and 1 bit time of J state. After this, the transmitter ceases to drive the D+/D− lines and the aforementioned pull up resistors hold it in the J (idle) state. Sometimes skew due to hubs can add as much as one bit time before the SE0 of the end of packet. This extra bit can also result in a "bit stuff violation" if the six bits before it in the CRC are 1s. This bit should be ignored by receiver.

Question: What is a USB packet's end called?

Question: What can skew due to hubs add?

Question: What can this extra bit result in?
Passage: USB 2.0 devices use a special protocol during reset, called chirping, to negotiate the high bandwidth mode with the host/hub. A device that is HS capable first connects as an FS device (D+ pulled high), but upon receiving a USB RESET (both D+ and D− driven LOW by host for 10 to 20 ms) it pulls the D− line high, known as chirp K. This indicates to the host that the device is high bandwidth. If the host/hub is also HS capable, it chirps (returns alternating J and K states on D− and D+ lines) letting the device know that the hub operates at high bandwidth. The device has to receive at least three sets of KJ chirps before it changes to high bandwidth terminations and begins high bandwidth signaling. Because USB 3.0 uses wiring separate and additional to that used by USB 2.0 and USB 1.x, such bandwidth negotiation is not required.

Question: What type of protocol is used for USB 2.0 devices during a reset?

Question: What is the special protocol during a USB 2.0 device reset called?

Question: A device that is HS capable first connects as a what?
Passage: According to routine testing performed by CNet, write operations to typical Hi-Speed (USB 2.0) hard drives can sustain rates of 25–30 MB/s, while read operations are at 30–42 MB/s; this is 70% of the total available bus bandwidth. For USB 3.0, typical write speed is 70–90 MB/s, while read speed is 90–110 MB/s. Mask Tests, also known as Eye Diagram Tests, are used to determine the quality of a signal in the time domain. They are defined in the referenced document as part of the electrical test description for the high-speed (HS) mode at 480 Mbit/s.

Question: Write operations to typical Hi-Speed hard drives can what?

Question: For USB 3.0, typical write speed is what?

Question: What is the read speed for USB 3.0?
Passage: After the sync field, all packets are made of 8-bit bytes, transmitted least-significant bit first. The first byte is a packet identifier (PID) byte. The PID is actually 4 bits; the byte consists of the 4-bit PID followed by its bitwise complement. This redundancy helps detect errors. (Note also that a PID byte contains at most four consecutive 1 bits, and thus never needs bit-stuffing, even when combined with the final 1 bit in the sync byte. However, trailing 1 bits in the PID may require bit-stuffing within the first few bits of the payload.)

Question: After the sync field, all packets are made of how many bit bytes?

Question: How are the bit bytes transmitted?

Question: The first byte is what?
Passage: Handshake packets consist of only a single PID byte, and are generally sent in response to data packets. Error detection is provided by transmitting four bits that represent the packet type twice, in a single PID byte using complemented form. Three basic types are ACK, indicating that data was successfully received, NAK, indicating that the data cannot be received and should be retried, and STALL, indicating that the device has an error condition and cannot transfer data until some corrective action (such as device initialization) occurs.

Question: Handshake packets consist of only a single what?

Question: When are handshake packets generally sent?

Question: What is provided by transmitting four bits that represent the packet type twice, in a single PID byte using complemented form?
Passage: IN and OUT tokens contain a seven-bit device number and four-bit function number (for multifunction devices) and command the device to transmit DATAx packets, or receive the following DATAx packets, respectively. An IN token expects a response from a device. The response may be a NAK or STALL response, or a DATAx frame. In the latter case, the host issues an ACK handshake if appropriate. An OUT token is followed immediately by a DATAx frame. The device responds with ACK, NAK, NYET, or STALL, as appropriate.

Question: IN and OUT tokens contain what?

Question: An IN token expects what?

Question: An OUT token is followed immediately by a what?
Passage: USB 2.0 also added a larger three-byte SPLIT token with a seven-bit hub number, 12 bits of control flags, and a five-bit CRC. This is used to perform split transactions. Rather than tie up the high-bandwidth USB bus sending data to a slower USB device, the nearest high-bandwidth capable hub receives a SPLIT token followed by one or two USB packets at high bandwidth, performs the data transfer at full or low bandwidth, and provides the response at high bandwidth when prompted by a second SPLIT token.

Question: a larger three-byte SPLIT token with a seven-bit hub number, 12 bits of control flags, and a five-bit CRC were created to do what?

Question: Rather than tie up the high-bandwidth USB bus sending data to a slower USB device, what happens?

Question: How many bits of control flags did USB 2.0 add?
Passage: There are two basic forms of data packet, DATA0 and DATA1. A data packet must always be preceded by an address token, and is usually followed by a handshake token from the receiver back to the transmitter. The two packet types provide the 1-bit sequence number required by Stop-and-wait ARQ. If a USB host does not receive a response (such as an ACK) for data it has transmitted, it does not know if the data was received or not; the data might have been lost in transit, or it might have been received but the handshake response was lost.

Question: There are two basic forms of data packet, what are they?

Question: A data packet must always be preceded by what?

Question: What is a data packet usually followed by?
Passage: Low-bandwidth devices are supported with a special PID value, PRE. This marks the beginning of a low-bandwidth packet, and is used by hubs that normally do not send full-bandwidth packets to low-bandwidth devices. Since all PID bytes include four 0 bits, they leave the bus in the full-bandwidth K state, which is the same as the low-bandwidth J state. It is followed by a brief pause, during which hubs enable their low-bandwidth outputs, already idling in the J state. Then a low-bandwidth packet follows, beginning with a sync sequence and PID byte, and ending with a brief period of SE0. Full-bandwidth devices other than hubs can simply ignore the PRE packet and its low-bandwidth contents, until the final SE0 indicates that a new packet follows.

Question: Low-bandwidth devices are supported with what?

Question: All PID bytes include how many 0 bits?

Question: Full-bandwidth devices other than hubs can what?
Passage: These and other differences reflect the differing design goals of the two buses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. Although similar in theoretical maximum transfer rate, FireWire 400 is faster than USB 2.0 Hi-Bandwidth in real-use, especially in high-bandwidth use such as external hard-drives. The newer FireWire 800 standard is twice as fast as FireWire 400 and faster than USB 2.0 Hi-Bandwidth both theoretically and practically. However, Firewire's speed advantages rely on low-level techniques such as direct memory access (DMA), which in turn have created opportunities for security exploits such as the DMA attack.

Question: These and other differences reflect the differing design goals of what?

Question: USB was designed for what?

Question: FireWire was designed for what?

Question: FireWire 400 is faster than what?
Passage: The IEEE 802.3af Power over Ethernet (PoE) standard specifies a more elaborate power negotiation scheme than powered USB. It operates at 48 V DC and can supply more power (up to 12.95 W, PoE+ 25.5 W) over a cable up to 100 meters compared to USB 2.0, which provides 2.5 W with a maximum cable length of 5 meters. This has made PoE popular for VoIP telephones, security cameras, wireless access points and other networked devices within buildings. However, USB is cheaper than PoE provided that the distance is short, and power demand is low.

Question: The IEEE 802.3af Power over Ethernet (PoE) standard specifies a what?

Question: Is USB cheaper or more expensive than PoE?

Question: What keeps USB cheaper than PoE?
Passage: Ethernet standards require electrical isolation between the networked device (computer, phone, etc.) and the network cable up to 1500 V AC or 2250 V DC for 60 seconds. USB has no such requirement as it was designed for peripherals closely associated with a host computer, and in fact it connects the peripheral and host grounds. This gives Ethernet a significant safety advantage over USB with peripherals such as cable and DSL modems connected to external wiring that can assume hazardous voltages under certain fault conditions.

Question: USB was designed for peripherals to be what?

Question: USB connects what?

Question: Ethernet standards require what?
Passage: eSATA does not supply power to external devices. This is an increasing disadvantage compared to USB. Even though USB 3.0's 4.5 W is sometimes insufficient to power external hard drives, technology is advancing and external drives gradually need less power, diminishing the eSATA advantage. eSATAp (power over eSATA; aka ESATA/USB) is a connector introduced in 2009 that supplies power to attached devices using a new, backward compatible, connector. On a notebook eSATAp usually supplies only 5 V to power a 2.5-inch HDD/SSD; on a desktop workstation it can additionally supply 12 V to power larger devices including 3.5-inch HDD/SSD and 5.25-inch optical drives.

Question: eSATA does not supply power to what?

Question: Even though USB 3.0's 4.5 W is sometimes insufficient to power external hard drives, technology is what?

Question: On a notebook eSATAp usually supplies how much power?
Passage: USB 2.0 High-Speed Inter-Chip (HSIC) is a chip-to-chip variant of USB 2.0 that eliminates the conventional analog transceivers found in normal USB. It was adopted as a standard by the USB Implementers Forum in 2007. The HSIC physical layer uses about 50% less power and 75% less board area compared to traditional USB 2.0. HSIC uses two signals at 1.2 V and has a throughput of 480 Mbit/s. Maximum PCB trace length for HSIC is 10 cm. It does not have low enough latency to support RAM memory sharing between two chips.

Question: USB 2.0 High-Speed Inter-Chip (HSIC) is a what?

Question: What does USB 2.0 High-Speed Inter-Chip eliminate?

Question: When was the USB 2.0 High-Speed Inter-Chip adopted as the standard by the USB Implementers Forum
Passage: Throughout its prehistory and early history, the region and its vicinity in the Yangtze region was the cradle of unique local civilizations which can be dated back to at least the 15th century BC and coinciding with the later years of the Shang and Zhou dynasties in North China. Sichuan was referred to in ancient Chinese sources as Ba-Shu (巴蜀), an abbreviation of the kingdoms of Ba and Shu which existed within the Sichuan Basin. Ba included Chongqing and the land in eastern Sichuan along the Yangtze and some tributary streams, while Shu included today's Chengdu, its surrounding plain and adjacent territories in western Sichuan.

Question: What was Sichuan referred to as by ancient Chinese sources?

Question: How far back can civilizations in the Yangtze region be dated?

Question: Where were the kingdoms of Ba and Shu located?

Question: What land was included in the kingdom of Ba?

Question: What land was included in the kingdom of Shu?
Passage: The existence of the early state of Shu was poorly recorded in the main historical records of China. It was, however, referred to in the Book of Documents as an ally of the Zhou. Accounts of Shu exist mainly as a mixture of mythological stories and historical legends recorded in local annals such as the Chronicles of Huayang compiled in the Jin dynasty (265–420), with folk stories such as that of Emperor Duyu (杜宇) who taught the people agriculture and transformed himself into a cuckoo after his death. The existence of a highly developed civilization with an independent bronze industry in Sichuan eventually came to light with an archaeological discovery in 1986 at a small village named Sanxingdui in Guanghan, Sichuan. This site, believed to be an ancient city of Shu, was initially discovered by a local farmer in 1929 who found jade and stone artefacts. Excavations by archaeologists in the area yielded few significant finds until 1986 when two major sacrificial pits were found with spectacular bronze items as well as artefacts in jade, gold, earthenware, and stone. This and other discoveries in Sichuan contest the conventional historiography that the local culture and technology of Sichuan were undeveloped in comparison to the technologically and culturally "advanced" Yellow River valley of north-central China. The name Shu continues to be used to refer to Sichuan in subsequent periods in Chinese history up to the present day.

Question: What did Emperor Duyu transform himself into after his death?

Question: What does the name Shu refer to?

Question: When was the site believed to be ancient city of Shu discovered, and by whom?

Question: The Shu were an ally of who, according to the Book of Documents?

Question: When were the Chronicles of Huayang compiled?
Passage: The rulers of the expansionist Qin dynasty, based in present-day Gansu and Shaanxi, were only the first strategists to realize that the area's military importance matched its commercial and agricultural significance. The Sichuan basin is surrounded by the Himalayas to the west, the Qin Mountains to the north, and mountainous areas of Yunnan to the south. Since the Yangtze flows through the basin and then through the perilous Yangzi Gorges to eastern and southern China, Sichuan was a staging area for amphibious military forces and a refuge for political refugees.[citation needed]

Question: What surrounds the Sichuan basin to the west?

Question: What mountains surround the Sichuan basin to the North?

Question: What river flows through the Sichuan basin?

Question: Where was the Qin dynasty based?

Question: What surrounds the Sichuan basin to the South?
Passage: Qin armies finished their conquest of the kingdoms of Shu and Ba by 316 BC. Any written records and civil achievements of earlier kingdoms were destroyed. Qin administrators introduced improved agricultural technology. Li Bing, engineered the Dujiangyan irrigation system to control the Min River, a major tributary of the Yangtze. This innovative hydraulic system was composed of movable weirs which could be adjusted for high or low water flow according to the season, to either provide irrigation or prevent floods. The increased agricultural output and taxes made the area a source of provisions and men for Qin's unification of China.

Question: By what year did the Qin armies finish their conquest of Shu and Ba?

Question: What did Qin administrators introduce to Shu and Ba?

Question: Who engineered the Dujiangyan irrigation system to control the Min River?

Question: The Min River is a major tributary of what river?

Question: The Dujiangyan irrigation system was used for what purpose?
Passage: Sichuan came under the firm control of a Chinese central government during the Sui dynasty, but it was during the subsequent Tang dynasty where Sichuan regained its previous political and cultural prominence for which it was known during the Han. Chengdu became nationally known as a supplier of armies and the home of Du Fu, who is sometimes called China's greatest poet. During the An Lushan Rebellion (755-763), Emperor Xuanzong of Tang fled from Chang'an to Sichuan. The region was torn by constant warfare and economic distress as it was besieged by the Tibetan Empire.

Question: During which dynasty did Sichuan regain its political and cultural prominence for which it was known during the Han?

Question: Who was known as China's greatest poet and lived in Chengdu?

Question: What was Chengu known to supply the country with?

Question: Which years saw the An Lushan Rebellion?

Question: Which empire ravished the Chengdu region with constant warfare and economic distress?