romikgosai/squad_modified_2 huggingface dataset:
USB device communication is based on pipes (logical channels). A pipe is a connection from the host controller to a logical entity, found on a device, and named an endpoint. Because pipes correspond 1-to-1 to endpoints, the terms are sometimes used interchangeably. A USB device could have up to 32 endpoints (16 IN, 16 OUT), though it's rare to have so many. An endpoint is defined and numbered by the device during initialization (the period after physical connection called "enumeration") and so is relatively permanent, whereas a pipe may be opened and closed.

Q1: What is a pipe?
A1: a connection from the host controller to a logical entity
Q2: A USB connection is based on what?
A2: pipes (logical channels)
Q3: What is a pipe named at?
A3: an endpoint
Q4: Where do pipes correspond?
A4: 1-to-1 to endpoints
Q5: How many endpoints can a USB device have?
A5: up to 32 endpoints
An endpoint of a pipe is addressable with a tuple (device_address, endpoint_number) as specified in a TOKEN packet that the host sends when it wants to start a data transfer session. If the direction of the data transfer is from the host to the endpoint, an OUT packet (a specialization of a TOKEN packet) having the desired device address and endpoint number is sent by the host. If the direction of the data transfer is from the device to the host, the host sends an IN packet instead. If the destination endpoint is a uni-directional endpoint whose manufacturer's designated direction does not match the TOKEN packet (e.g. the manufacturer's designated direction is IN while the TOKEN packet is an OUT packet), the TOKEN packet is ignored. Otherwise, it is accepted and the data transaction can start. A bi-directional endpoint, on the other hand, accepts both IN and OUT packets.

Q1: If the direction of the data transfer is from the device to the host, what does the host send?
A1: the host sends an IN packet
Q2: What does a bi-directional endpoint accept?
A2: both IN and OUT packets
Q3: What is sent if the direction of the data transfer is from host to endpoint?
A3: an OUT packet
When a USB device is first connected to a USB host, the USB device enumeration process is started. The enumeration starts by sending a reset signal to the USB device. The data rate of the USB device is determined during the reset signaling. After reset, the USB device's information is read by the host and the device is assigned a unique 7-bit address. If the device is supported by the host, the device drivers needed for communicating with the device are loaded and the device is set to a configured state. If the USB host is restarted, the enumeration process is repeated for all connected devices.

Q1: What is started when a USB is first connected to a host?
A1: enumeration process
Q2: What id the data rate determined during?
A2: the reset signaling
Q3: When is the device assigned a unique 7-bit address?
A3: After reset
Q4: What does the enumeration process start by doing?
A4: sending a reset signal to the USB device
Q5: What happens whenever a USB host is restarted?
A5: the enumeration process is repeated for all connected devices.
High-speed USB 2.0 hubs contain devices called transaction translators that convert between high-speed USB 2.0 buses and full and low speed buses. When a high-speed USB 2.0 hub is plugged into a high-speed USB host or hub, it operates in high-speed mode. The USB hub then uses either one transaction translator per hub to create a full/low-speed bus routed to all full and low speed devices on the hub, or uses one transaction translator per port to create an isolated full/low-speed bus per port on the hub.

Q1: What do transaction translators do?
A1: convert between high-speed USB 2.0 buses and full and low speed buses
Q2: When does a USB 2.0 hub operate in high speed mode?
A2: When a high-speed USB 2.0 hub is plugged into a high-speed USB host or hub
Q3: What kind of devices do High speed USB 2.0's contain?
A3: transaction translators
USB implements connections to storage devices using a set of standards called the USB mass storage device class (MSC or UMS). This was at first intended for traditional magnetic and optical drives and has been extended to support flash drives. It has also been extended to support a wide variety of novel devices as many systems can be controlled with the familiar metaphor of file manipulation within directories. The process of making a novel device look like a familiar device is also known as extension. The ability to boot a write-locked SD card with a USB adapter is particularly advantageous for maintaining the integrity and non-corruptible, pristine state of the booting medium.

Q1: What do USB's implement connections to?
A1: storage devices
Q2: What are the standards called that implement connections to storage devices?
A2: the USB mass storage device class (MSC or UMS)
Q3: What is the process of making a novel device look like a familiar device?
A3: extension
Q4: Why is the ability to boot write-locked SD cards with a USB adapter advantageous for?
A4: maintaining the integrity and non-corruptible, pristine state of the booting medium.
Though most computers since mid-2004 can boot from USB mass storage devices, USB is not intended as a primary bus for a computer's internal storage. Buses such as Parallel ATA (PATA or IDE), Serial ATA (SATA), or SCSI fulfill that role in PC class computers. However, USB has one important advantage, in that it is possible to install and remove devices without rebooting the computer (hot-swapping), making it useful for mobile peripherals, including drives of various kinds (given SATA or SCSI devices may or may not support hot-swapping).

Q1: Since when can most computers boot from USB mass storage devices?
A1: since mid-2004
Q2: What is USB not intended for?
A2: a primary bus for a computer's internal storage
Q3: What is an important advantage of USB?
A3: it is possible to install and remove devices without rebooting the computer
Q4: Buses such as Parallel ATA fulfill what role in PC computers?
A4: a computer's internal storage
Firstly conceived and still used today for optical storage devices (CD-RW drives, DVD drives, etc.), several manufacturers offer external portable USB hard disk drives, or empty enclosures for disk drives. These offer performance comparable to internal drives, limited by the current number and types of attached USB devices, and by the upper limit of the USB interface (in practice about 30 MB/s for USB 2.0 and potentially 400 MB/s or more for USB 3.0). These external drives typically include a "translating device" that bridges between a drive's interface to a USB interface port. Functionally, the drive appears to the user much like an internal drive. Other competing standards for external drive connectivity include eSATA, ExpressCard, FireWire (IEEE 1394), and most recently Thunderbolt.

Q1: Several manufacturers offer what?
A1: external portable USB hard disk drives
Q2: What do external portable USB hard drive disks offer?
A2: performance comparable to internal drives
Q3: What is the most recent standard for external drive connectivity?
A3: Thunderbolt
Q4: What do the external drives typically include?
A4: a "translating device"
Media Transfer Protocol (MTP) was designed by Microsoft to give higher-level access to a device's filesystem than USB mass storage, at the level of files rather than disk blocks. It also has optional DRM features. MTP was designed for use with portable media players, but it has since been adopted as the primary storage access protocol of the Android operating system from the version 4.1 Jelly Bean as well as Windows Phone 8 (Windows Phone 7 devices had used the Zune protocol which was an evolution of MTP). The primary reason for this is that MTP does not require exclusive access to the storage device the way UMS does, alleviating potential problems should an Android program request the storage while it is attached to a computer. The main drawback is that MTP is not as well supported outside of Windows operating systems.

Q1: Media Transfer Protocol was designed by who?
A1: Microsoft
Q2: Why was Media Transfer Protocol designed?
A2: to give higher-level access to a device's filesystem
Q3: What was MTP originally designed for?
A3: use with portable media players
Q4: Why has MTP become the primary storage access protocol of the Android operating system?
A4: MTP does not require exclusive access to the storage device the way UMS does
USB mice and keyboards can usually be used with older computers that have PS/2 connectors with the aid of a small USB-to-PS/2 adapter. For mice and keyboards with dual-protocol support, an adaptor that contains no logic circuitry may be used: the hardware in the USB keyboard or mouse is designed to detect whether it is connected to a USB or PS/2 port, and communicate using the appropriate protocol. Converters also exist that connect PS/2 keyboards and mice (usually one of each) to a USB port. These devices present two HID endpoints to the system and use a microcontroller to perform bidirectional data translation between the two standards.

Q1: What do older computers have to have in order for USB mice and keyboards to be used?
A1: PS/2 connectors with the aid of a small USB-to-PS/2 adapter
Q2: What is the hardware designed to detect in USB mice and keyboards?
A2: whether it is connected to a USB or PS/2 port
Q3: USB keyboards and mice may communicate using what?
A3: appropriate protocol
Q4: What connects PS/2 keyboards and mice to a USB port?
A4: Converters
Q5: What performs bidirectional data translation between two standards?
A5: a microcontroller
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.

Q1: What is difficult to do with a USB plug?
A1: to insert a USB plug into its receptacle incorrectly
Q2: The USB specification states that the required USB icon must be what?
A2: embossed on the "topside" of the USB plug
Q3: How is the USB icon located to each receptacle?
A3: adjacent
Q4: Receptacles should be oriented to allow the icon on the plug to what?
A4: to be visible during the mating process
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.

Q1: What do Type-A receptacles do on host devices?
A1: supply power
Q2: What do Type-b receptacles do on target devices?
A2: draw power
Q3: What do the receptacles prevent user from doing?
A3: from accidentally connecting two USB power supplies to each other
Q4: What networks do USB not support?
A4: cyclic networks
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.

Q1: Standard connectors were designed to be what?
A1: robust
Q2: Why were standard connectors designed to be so robust?
A2: the connectors would be used more frequently
Q3: What as a drawback of previous connectors?
A3: Many previous connector designs were fragile
Q4: How are the electrical contents of a USB connector protected?
A4: by an adjacent plastic tongue
Q5: How is the entire connecting assembly of a USB connector protected?
A5: by an enclosing metal sheath
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.

Q1: Where is the external metallic sheet connected?
A1: typically connected to system ground
Q2: What provides a degree of protection from interference with the USB signal?
A2: This enclosure design
Q3: This type of stage make-break timing allows for what?
A3: electrically safe hot-swapping.
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.

Q1: What are the newer micro-USB receptacles designed for?
A1: a minimum rated lifetime of 10,000 cycles of insertion
Q2: What is the minimum rated lifetime for the standard USB receptacle?
A2: 1,500
Q3: After a leaf-spring was moved from jack to the plug, the most stressed part was found where?
A3: on the cable side of the connection
Q4: Why was the change made for the USB device?
A4: so that the connector on the less expensive cable would bear the most wear
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.

Q1: What type of tolerances does the USB standard specify for compliant USB connectors?
A1: loose tolerances
Q2: Why were loose tolerances allowed for compliant USB connectors?
A2: to minimize physical incompatibilities in connectors from different vendors
Q3: How is a weakness addressed in some other connector standards?
A3: the USB specification also defines limits to the size of a connecting device
Q4: Due to size restrictions compliant devices must what?
A4: fit within the size restrictions or support a compliant extension cable that does
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.

Q1: USB cables and device have only what on their ends?
A1: plugs
Q2: Hosts and devices only have what in terms of connecting to a USB device?
A2: receptacles
Q3: Devices usually have what type of receptacle?
A3: one or another Type-B variety
Q4: Hosts almost always have what type of receptacle?
A4: Type-A receptacles
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.

Q1: What has been used to connect digital cameras. smartphones and other devices to tablet computers?
A1: Various connectors
Q2: What was standard for transferring data to and from the earlier type of smartphones?
A2: The mini-B USB connector
Q3: How large are both mini-A and mini-B plugs?
A3: approximately 3 by 7 mm
Q4: When were the mini-A connector and and the mini-AB receptacle connector depreceated?
A4: 23 May 2007
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.

Q1: What is the micro connector designed for?
A1: to reduce the mechanical wear on the device
Q2: What is the easier-to-replace cable designed for?
A2: to bear the mechanical wear of connection and disconnection
Q3: What is the micro-plug rated for?
A3: 10,000 connect-disconnect cycles
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."

Q1: In 2007 who endorsed micro-USB as the standard connector for data and power on mobile devices?
A1: The cellular phone carrier group Open Mobile Terminal Platform
Q2: When did the ITU announce that it had embraced micro-USB as the Universal Charging Solution?
A2: 22 October 2009
Q3: What has energy-efficient one-charger-fits-all new mobile phone solution?
A3: micro-USB
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.

Q1: Who defined a common External Power Supply for use with smartphones sold?
A1: The European Standardisation Bodies CEN, CENELEC and ETSI
Q2: How many mobile phone manufacturers signed the EU's common EPS (MoU)?
A2: 14
Q3: Who was one of the original MoU signers?
A3: Apple
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.

Q1: What are all USB On-The-Go devices required to have?
A1: one, and only one, USB connector
Q2: Non-OTG compliant devices are not allowed to use what?
A2: the micro-AB receptacle
Q3: Why are the Non-OTG compliant devices not allowed to use the micro-AB receptacle?
A3: power supply shorting hazards on the VBUS line
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.

Q1: The OTG device with the B-plug inserted is called what?
A1: B-device
Q2: What does an OTG device default to with no plug inserted?
A2: to acting as a B-device
Q3: What is the A-device responsible for?
A3: powering the USB interface when required
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.

Q1: What is USB?
A1: a serial bus
Q2: What kind of wires does the USB 2.0 variant use?
A2: four shielded wires
Q3: What are the four shielded wires in the USB 2.0 variant used for?
A3: two for power (VBUS and GND), and two for differential data signals