[net.graphics] Need graphics interface for vt100 with AVO

gwyn@brl-vgr.ARPA (Doug Gwyn ) (05/15/84)

The VT100 Advanced Video Option does not let your VT100 do graphics.
It merely adds individual text character attributes (bold, blinking,
underlined, etc.).  For real graphics you need a Selanar, DEI
RetroGraphics, or similar addition.

dan@rna.UUCP (05/15/84)

Hi,
	re: vt100 graphics

	I don't believe it is possible to produce decent graphics of the
style promoted by plot(3) with a VT100 with AVO. All that the AVO provides
the VT100 over a standard ANSI-like 24x80 terminal is
	- 24x132 format
	- blink, bold, underline
	- an extra character ROM

	For a VT100 to produce decent vector-type graphics, one needs an
add-on board such as the VT125, or the Retrographics or Selanar.

	However it is possible to get crude "graphics" out of the VT100.
The best scheme I have heard is to put the VT100 in 24x132 mode and use
the 1,3,5,7,9 scan line set of the special graphics character. These
scan line characters essential turn on the particular scan line for that
character position, e.g. a '-' is basically scan line 5.
	Thus one has a system of producing crude plots with 132-X points
and 5x24 or 120-Y points. A given character position can only display
one of the possible 5 Y values, however.
	This scheme is probably adequate for simple 1 or 2 valued plots.

	I am sure better hooks for graphics are available for the Macintosh.

					Cheers,
					Dan Ts'o
					...cmcl2!rna!dan