AST 4 Port

In 1991 SDF expanded to 4 dialups and made use of the AST 4 Port ISA adapter to allocate 4 serial ports to a single PC interrupt for ISC 386/ix UNIX using the FAS driver along with the standard 2 COM ports. In 1993 a second AST 4 Port was and the FAS driver was modified to support it. This allowed SDF to expand to a total of 10 dialup lines at the Sojourn, Addison Texas location.