Technical data

Block Diagram
A-5
DIGITAL Server 5220
System I/O
The System I/O controls the system input and output functions for the serial
interface, the parallel interface, the diskette controller, the keyboard, and the mouse.
Ultra I/O Controller
The system input and output functions are controlled by the Ultra I/O controller, SMC
37C935APM. This controller supports two serial UARTs, one parallel port, and the
diskette controller. It provides a buffer for the serial ports and EPP/ECP modes for
the parallel port. It also provides the keyboard/mouse ports and the real time clock
(RTC).
Serial Interface
The Serial interface ports (COM1 and COM2) are implemented on the main logic
board and are accessible through the rear panel 9-pin D-subminiature connectors.
These connectors are functionally compatible with RS-232C standards. The table
below lists the serial interface pin assignments.