What are the advantages of USB over serial ports?

Answer 1

Serial ports are an old endpoint connector style and signal protocol. USB is an end-to-end universal bus architecture. You can't really compare the two directly, but as USB has in practice generally replaced the RS232 serial protocol, there are some similarities in features to be drawn and compared. * SpeedSerial ports transmit a single bit of information every clock cycle. The clock rates range from anywhere between 150 to 119200 at mathematically convenient intervals. (150, 300, 1200, 2400, 4800, 9600, 14400, 28800, 38400 and 57600 have all been common values.) At 119200bps (bits per second), divided by 8 (bits per byte), that's 14900 bytes per second, or roughly 14.5K/s of total bandwidth. To put that in perspective, an average cable internet speed cap is about 10Mbps, or about 83 times faster. Common network signalling speed is 100Mpbs, or 830 times the potential of a typical serial port. You could not use these services over a serial connection. On the other hand, USB 2.0 is capable of speeds of up to 480Mbps. That's 480 million bits per second. That's roughly four thousand times the maximum potential speed of a serial port clocking at 119200bps. However, the real speed of USB to or from any particular device generally depends on the device itself, other devices connected to the same bus, or other limitations on the host PC. * Connectivity Serial ports primarily feature D-style connectors of either 9 or 25 pins. They're fairly large by today's standards, and even before USB was introduced it was rare for any system to have more than two. Additionally, only a single endpoint device could be plugged into a single serial port (mouse, modem, printer, data line, etc). USB connectors have a total of four (sometimes five) contacts. This allows the plugs and jacks to be very small. USB has a myriad of physical connector styles for many different types of devices, though they're all still USB standard -- they all speak the same language. Additionally, since USB is a bus and not just an endpoint connector, it can be extended via the use of USB hubs to provide additional connectors for additional devices on the same USB connection (up to 256 per host port). * Availability Due to the smaller size of USB connectors, modern computers may feature up to four to eight or more USB ports, with more connections available via USB hubs. Additionally, a great deal of consumer perphierals are now offered as USB devices. Serial ports and serial devices are now usually relegated to legacy hardware or specialized uses. * Power USB ports supply a 5 volt power line in addition to the signalling lines from which some USB devices may draw in order to power themselves, allowing for lower power peripherals to require only a single connector - USB - instead of having additional cords or cables for power as well. This is particularly important in a portability context; most laptop users prefer not to have to carry plug-in power supplies for every peripheral, as well as having to find an electrical outlet for each one. Smaller devices such as USB card readers or even external hard drives can now simply use a single USB plug to be ready for use. This also allows for additional functionality such as charging a device's battery from the USB connector. (In fact, some devices such as certain models of cellular phones have USB plugs specifially for that purpose; they may not actually communicate at all over USB, they're just using the power from a USB connection to charge the batteries, since USB is now so common and highly available.) * Plug and Play and device abstraction The typical usage model of a serial device involved the controlling software sending commands to and from the serial controller chip (UART), which then communicated over the serial line to the device. The system itself didn't generally know exactly what device was plugged in, or even if there was anything plugged in at all. It simply expected a certain protocol to be followed to and from the COM port, depending on what the software was written for. This was in an age before modern multitasking and OS driver models, and led to many serial devices requiring proprietary software to use at all, which in turn led to many compatibility issues as systems advanced over time and controlling software was not updated, making the device itself unusable. The nature of the USB architecture and the more modern nature of it's controlling hardware allows for USB devices to be added or removed on the fly, and the devices themselves to be directly detected by the host system and, if necessary, drivers installed, just like any other piece of system hardware. The device can then be univerally used in the operating system and with any software designed to operate that class of device (input, audio, storage, etc).

Answer 2

USB: Is a port that can connect computer peripherals such as mouse devices, keyboards, PDAs, game pads and joysticks, scanners, digital cameras and printers. For many of those devices USB has become the standard connection method.

SERIAL: Is a port is a serial communication physical interface through which information transfers in or out one bit at a time (contrast parallel port). Throughout most of the history of personal computers, data transfer through serial ports connected the computer to devices such as terminals or modems. Mice, keyboards, and other peripheral devices also connected in this way.

NOTE: The USB has now retired the use of Serial Connection!

The USB is now the Standard of Connection between two or more Peripherals.

Hope that helps!!

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Answer 3

There are two advantages... Firstly, convenience - A USB port is 'hot' - meaning that devices can be connected or unplugged without switching the device off. Secondly, speed - USB devices communicate much faster with the host computer.

Answer 4

Yes. A USB port is many times faster than a traditional serial port. A USB port also does not have easily breakable pins.

Answer 5

Because it was designed to transfer data faster.