Serial port requiring programs to refer to them by hardware address. Unix-like operating systems usually label the serial port devices /dev/tty*. "TTY" is a common trademark-free abbreviation for "teletype", a device commonly attached to early computers' serial ports, and * represents a string identifying the specific port; the syntax of that string depends on the operating system and the device. On Linux, 8250/16550 UART hardware serial ports are named /dev/ttyS*, USB adapters appear as /dev/ttyUSB* and various types of virtual serial ports do not necessarily have names starting with tty. The DOS and Windows environments refer to serial ports as COM ports:
Sun-1 It was also the console port if no graphical display was installed in the system. Serial port B was wired as a Data Terminal Equipment (DTE) port and had no modem control. Both serial ports could also be used as terminal ports and quite often were allowing 3 people to use one workstation, although two did not have graphical displays. The 16-bit parallel port was a special purpose port for connecting 8-bit parallel port keyboard and 8-bit parallel port optical mouse for workstations with graphical displays. The parallel port was never used as a general purpose parallel printer port. The