The Hall Technologies DVS-4A is a versatile and compact 4 input x 1 output DVI & audio switch. This unit provides both a video and audio output that can be switched between four video and audio sources. This allows routing of multiple DVI equipped devices (such as PC's) to a single DVI display (such as a plasma or LCD screen). The switcher supports single-link, DVI-D video signals at resolutions up to 1920x1200 and HDTV up to 1080p. The DVS-4A unit provides all the A/V and control connections on the rear panel; the front panel has a push-button switch with corresponding LED indicator for the selection of video source. This unit can be controlled by either manually using the front panel switch, automatically based on video detection, or remotely through an RS232 serial port. The unit can be configured to operate in three different modes, which are the Auto, Scan and Manual modes. The unit also has EEPROM (internal non-volatile flash memory) to store the last operating mode when power is off.