12.1 Overview

Helios contains four 16550-style asynchronous serial ports derived from the Vortex86 processor. Each port has 16-character transmit and receive FIFOs and is capable of transmitting at speeds of 9600, 19.2K, 38.4K, 57.6K, or 115.2Kbaud. The default settings for all ports are 115.2K, N, 8, 1.

Ports 1 and 2 can be jumper-configured for RS-232, RS-422, or RS-485, and ports 3 and 4 are fixed RS-232. The transceivers provide 15KV ESD protection. In RS-422 and RS-485 mode, 120 ohm line termination can be enabled by jumper. In RS-422 mode, receiver biasing can be jumper selected to force the inputs to an inactive state.

Console redirection is available on any one port, COM1 – 4. This feature enables keyboard input and character video output to be routed to one of the serial ports. Console operation can be configured in the BIOS to be enabled during POST (power on self test before the operating system loads), always on, or always off.