- Ports are critical to allow information to flow in and out of the
computer system
- Each I/O device is connected to an interface called a port
- Each port is connected to I/O or device controller
- It is the device controller that handles the interaction between the
CPU and I/O device
- Ports are internal if the connected I/O device is an integral part
of the computer system.
- External ports connect I/O devices and are called peripherals
- Early days of Ports
- Prior to Plug ‘n’ Play (PnP), computer users had to understand a lot
of the technical aspects between attaching peripheral devices to
computers
- The user was responsible for loading the correct driver and
configuring the port settings (which was fairly technical)
- PnP and the USB
- PnP attempted to solve the problem of configuring with the concept
of plugging in a device, and being able to use it straight away
- USB helped this concept enormously by providing a port which
could support different devices with one connector style
- USB allows:
- Chaining of devices (up to 127 devices per hub)
- Devices can be attached without having to power down
- Devices are detected and automatically configured for use (with
an up-to-date OS)
- Evolving standard with faster communications
- USB-C
- As USB grew in popularity its standards were being constantly
stretched.
- E.g. the standard type-A connector was too big for mobile
phones, etc.
- Different USB cables became a nightmare to manage
- USB-C’s aim is simple but huge
- Replace every connector with USB-C
- USB-C can:
- Deliver 100W (while still communicating)
- Eradicating the need for proprietary laptop chargin
units
- Deliver HDMI/DisplayPort/VGA output
- Very small and reversible (plugs in both way)
- Works well with USB standard 3.1
- In summary USB:
- Detects devices automatically and configures for use when first
attached. This functionality is called plug and play
- It is nearly impossible to wrongly connect a device
- Has become an industrial standard
- Later versions are backwards compatible with earlier standards
- Allows power to be drawn to charge portable devices
- USB 3 has improved this enormously
- Later versions (USB 3) allow full duplex data transfer
- Is supported by many operating systems