More on this book
Kindle Notes & Highlights
by
Mike Meyers
Started reading
August 2, 2021
A USB host controller is the boss, the master, of any device (the slave) that plugs into that host controller.
The host controller sends commands and provides powe...
This highlight has been truncated due to consecutive passage length restrictions.
The host controller is upstream, controlling devices co...
This highlight has been truncated due to consecutive passage length restrictions.
The host controller is shared by every device plugged into it, so speed and power are red...
This highlight has been truncated due to consecutive passage length restrictions.
USB Standards and Compatibility The USB standard has gone through several revisions: • USB 1.1 was the first widely adopted standard and defined two speeds: Low-Speed USB, running at a maximum of 1.5 Mbps (plenty for keyboards and mice), and Full-Speed USB, running at up to 12 Mbps. • The USB 2.0 standard introduced Hi-Speed USB running at 480 Mbps. • USB 3.0 is capable of speeds of up to 5 Gbps—ten times faster than USB 2.0. USB 3.0 is marketed as SuperSpeed USB. It’s also referred to as USB 3.1 Gen 1, though not on the CompTIA A+ exams. • USB 3.1 can handle speeds up to 10 Gbps. It’s
...more
USB 2.0 is fully backward compatible with USB 1.1 devices, while USB 3.0/3.1 is backward compatible with USB 2.0 devices.
EXAM TIP The USB Implementers Forum (USB-IF) does not officially use “Low-Speed” and “Full-Speed” to describe 1.5-Mbps and 12-Mbps devices, calling both simply “USB 1.1.” The CompTIA A+ certification exams, though, traditionally refer to the marketplace-standard nomenclature used here.
Motherboards capable of both USB 1.1 and USB 2.0 usually share the available USB ports (see Figure 10-5). For every USB port on your computer, a Low-Speed or Full-Speed device uses the USB 1.1 host controller, whereas a Hi-Speed device uses the USB 2.0 host controller.
USB 3.0 and 3.1, on the other hand, are different enough from USB 2.0 that they typically use separate host controllers. You can plug older USB devices into a USB 3.0 or 3.1 port, as noted, but they will run at the slower speeds. The only ports that work at 10 Gbps are the USB 3.1 ports
USB Cables and Connectors
When USB 1.1 was introduced, the standard defined two types of connectors: USB A and USB B. USB A connectors plug upstream toward the host controller (which is why you see them on the PC) and USB B connectors plug downstream into USB devices.
The A and B plugs come in sizes: “standard” USB A/USB B, mini USB A/mini USB B, an...
This highlight has been truncated due to consecutive passage length restrictions.
The mini and micro USB A connectors were basically ignored; most devices come hard wired. The mini USB B and micro USB B connect smaller d...
This highlight has been truncated due to consecutive passage length restrictions.
EXAM TIP The naming conventions for USB Type-C connectors are all over the place, just like with A and B connectors. A lot of industry folks shorten and hyphenate the connector to USB-C. That’s also how you’ll see it on the CompTIA A+ 1001 exam.
USB Type-C is quickly replacing Micro-USB as the dominant USB connection for devices
