ReGIS

ReGIS, short for Remote Graphic Instruction Set, was a vector graphics markup language developed by Digital Equipment Corporation (DEC) for later models of their famous VT series of computer terminals. ReGIS supported rudimentary vector graphics consisting of lines, circular arcs, and similar shapes. Terminals supporting ReGIS generally allowed graphics and text to be mixed on-screen, which made construction of graphs and charts relatively easy.

ReGIS was first introduced on the VT125 in July 1981, followed shortly thereafter by the VK100 "GIGI" which combined the VT125 display system with composite video output and a BASIC interpreter. Later versions of the VT series included ReGIS, often with color support as well. This included the VT240 and 241 and the VT330 and 340. ReGIS is also supported by a small number of terminal emulator systems.

ReGIS replaced an earlier system known as waveform graphics that had been introduced on the VT55 and later used on the VT105. DEC normally provided backward compatibility with their terminals, but in this case the waveform system was simply dropped when ReGIS was introduced.

ReGIS consisted of five primary drawing commands and a selection of status and device control commands. ReGIS mode was entered by specifying the escape code sequence ESCP0p, and exited with ESC\. The sequence ESCP is the generic Device Control String (DCS) used in the VT series of terminals, and is also used for a variety of other commands. The digit following the DCS was optional and specified a mode, in this case mode 0. Mode 0 was the default and picked up drawing where it left off, 1 reset the system to a blank slate, and 2 and 3 were the same as 0 and 1, but left a single line of text at the bottom of the screen for entering commands.

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