This was used by DEC to dial in to the computer over a telephone line and manage it as though someone were typing at the console. It used an unpublished protocol between the kit at DEC's end ad the box at your end. Technically the box still belongs to DEC ... or maybe COMPAQ ... or soon HP. The support engineer at DEC's end could do whatever he liked to your machine, but everyhting he did was recorded by the support centre's systems. Antonio