UNIVAC Uniscope

A Uniscope was a class of terminals made by Sperry Rand Corporation, Univac Division, and successors since 1964 that were normally used to communicate with Univac mainframes. As such, it was the successor to various models of Teletype. Due to the text color on the original models, these terminals are informally known as green screen terminals. Unlike Teletype terminals, the Uniscope minimizes the number of I/O interrupts required by accepting large blocks of data, and uses a high speed proprietary communications interface, using coax cable and hardware devices known as multiplexors. A Uniscope operator awaits a prompt from the remote mainframe. The prompt indicates that the mainframe is ready to receive input. The operator enters data, offline from the mainframe, and then presses the Transmit button. The terminal locks the keyboard and sends to the mainframe what the operator entered. All the data goes in a single transmission and that causes a single interrupt at the mainframe. Eventually, the mainframe responds, sometimes with a single line; other times with a screen-load of data. And the cycle repeats.