The display driver will typically accept commands and data using an industry-standard general-purpose serial or parallel interface, such as TTL, CMOS, RS232, SPI, voltage, current, timing and demultiplexing to make the display show the desired text or image.
Others include the keyboard, mouse, RS232 and Centronics servers (built into the host I/O server), the null server (like Unix's /dev/null), and the logger server (like Unix's syslog).
Depending on the vendor, drivers may be available that can communicate over USB, RS232, RS485, or even an Ethernet connection.