DEC Regis Terminals

T. J. Pearson, 1988.
Supported devices
Digital Equipment Corporation VT125, VT240, or VT241 terminal; other REGIS devices may also work.
Device type code
Default file name
TT:PGPLOT.VTPLOT. This usually means the terminal you are logged in to (logical name TT), but the plot can be sent to another terminal by giving the device name, e.g., TTC0:/VT, or it can be saved in a file by specifying a file name (in this case a disk name must be included as part of the file name).
Default view surface dimensions
Depends on monitor.
The default view surface is 768 (horizontal) by 460 (vertical) pixels. On most Regis devices, the resolution is degraded in the vertical direction giving only 230 distinguishable raster lines. (There are actually 240 raster lines, but 10 are reserved for a line of text.)
Color capability
Color indices 0--3 are supported. By default, color index 0 is black (the background color). Color indices 1--3 are white, red, and green on color monitors, or white, dark grey, and light grey on monochrome monitors. The color representation of all the color indices can be changed, although only a finite number of different colors can be obtained (see the manual for the terminal).
Input capability
The graphics cursor is a blinking diamond-crosshair. The user positions the cursor using the arrow keys and PF1--PF4 keys on his keyboard [Note: NOT the keyboard of the terminal on which he is plotting, if that is different.] The arrow keys move the cursor in the appropriate direction; the size of the step for each keystroke is controlled by the PF1--PF4 keys: PF1 = 1 pixel, PF2 = 4 pixels, PF3 = 16 pixels, PF4 = 64 pixels. [The VT240 terminal has a built-in capability to position the cursor, but PGPLOT does not use this as it is not available on the VT125.] The user indicates that the cursor has been positioned by typing any character other than an arrow or PF1--PF4 key [control characters, eg, ctrl-C, and other special characters should be avoided, as they may be intercepted by the operating system].
File format
A REGIS plot file is formatted in records of 80 characters or less, and has no carriage-control attributes. The records are grouped into ``buffers,'' each of which begins with a command to put the terminal into graphics mode and ends with a command to put it back into text mode. The terminal is in graphics mode only while a buffer is being transmitted, so a user's program can write to the terminal at any time (in text mode) without worrying if it might be in graphics mode.
Obtaining hardcopy
A hardcopy of the plot can be obtained using a printer attached to the VT125/VT240 terminal (see the instruction manual for the terminal). A plot stored in disk file can be displayed by issuing a TYPE command (e.g., TYPE PGPLOT.VTPLOT) on a VT125 or VT240.