Serial I/O communication

1. Universal Serial Bus (USB) - This will attach all sorts of external USB devices commonly includes external hard drive, printer and scanner, mouse and keyboard. With USB Type C, computers and smartphones now offer connections to each other.
2. Ethernet - provides connection between an end device and a network. It can offer I/O speeds of up to 1000 Megabits per seconds. Some types includes Coaxial, RJ45 and the latest is the Fiber Optic cables.
3. Peripheral Component Interconnect Express (PCIe) - Is a standard type of user interface link for internal interfaces like Graphics Processing Units. The PCI Express protocol, as well as other equipment, enables high speed connectivity between devices and motherboard.
4. Firewire (IEEE 1394) - Is a standard serial bus interface for high-speed communications and real-time I/O data transmission.
5. Serial Advanced Technology Attachment Express(SATAe) - This is an interface which is used to link ATA hard drives to the motherboard of a device. This supports both SATA and PCIe storage devices.

Parallel I/O communication

1. Parallel port - The parallel port is located on the back of computers that are compliant with IBM and is a 25-pin (DB-25 type) device interface typically used to link printers to the machine.
2. Parallel Advanced Technology Attachment (PATA) - Parallel ATA (PATA), originally named AT Attachment, is a standard interface for attaching storage devices in computers such as disk drives, floppy disk drives, and optical disks.
3. Front-side Bus (FSB) - A front-side bus (FSB) is a network networking bus that was mostly in computers built on Intel-chips. It carries data between the CPU and memory controller hub known as northbridge.
4. IEEE 1284 - is a standard which specifies simultaneous I/O parallel communication between computers and other devices. It was initially established by Centronics in the 1970s and became commonly recognized as the Centronics terminal, both before and after its standardization with IEEE.
5. Small Computer System Interface (SCSI) - is more widely used with hard disk drives and cassette drives although it can connect a large range of other items, including scanners and CD players, but not all controllers can accommodate these items.