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Conference atlant::terminals

Title:Traditional Video Terminals and Monitors
Notice:See 3230 for Sun River information
Moderator:REGENT::LASKO
Created:Tue Mar 18 1986
Last Modified:Thu May 22 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3256
Total number of notes:14159

3255.0. "Identify VT3xx terminal vs emulator via GETDVI?" by PATE::COTE (Dave Cote, Hudson,MA.USA dtn 225-4166) Mon May 12 1997 15:05

	How can I determine from within a program, eg. using Lib$Getdvi
	whether the user is on a physical VT3xx terminal vs using an emulator?

								Thanks, Dave
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3255.1PCBUOA::BAYJJim, PortablesMon May 12 1997 15:4323
    If the emulator identifies itself as a specific terminal, like a 300 or
    400 series, then theoretically you can't.  That is, the OS is supposed
    to believe the id string, and an emulator will typically send the id
    string exactly as the terminal would send it, because applications that
    depend on a specific terminal type might break if the id string is not
    correct.
    
    That said, the VT series had many different attribute return functions
    that might be helpful for "guessing" what device you are talking to. 
    
    For example, a VT 400 series has a certain number of video page memory
    available.  Most terminal emulators don't limit you to the physical
    amount that a terminal actually has.  By querying the terminal using
    one of the advanced characteristic calls, you might be able to find out
    the amount of video memory, and guess its a terminal emulator.
    
    Its a real catch-22.  A good emulator won't give away that its not a
    terminal.  In order to really identifiy itself, a non-standard method
    has to be set up, which makes the emulator no longer appear to be an
    exact duplicate of the terminal its emulating.
    
    jeb
    
3255.2JAMIN::OSMANEric Osman, dtn 226-7122Mon May 12 1997 16:287
Given that a hotsy totsy emulator won't give itself away, it might
be interesting to ask you back why your program wants to know whether
it's running on an emulator or not.

When YOU answer that question, maybe it will give a clue as to what you
can do instead of asking whether the program is on an emulator or not.
3255.3ReGIS mouse flakinessPATE::COTEDave Cote, Hudson,MA.USA dtn 225-4166Mon May 12 1997 18:0610
	Thanks for the quick responses!

	I have a program that was written several years ago using the
	ReGIS mouse on the VT3xxs to select items on screen.

	Now, some of those VTs are being replaced with windows
	systems, e.g. VXT's, satellites and PCs
	and I can't get the mouse to work transparently across
	VT & windows platforms, so ...
	if I can differentiate I'll just make the switch internally.   Dave
3255.4Flaky mouse detailsPATE::COTEDave Cote, Hudson,MA.USA dtn 225-4166Tue May 13 1997 10:3610
	Here's a little more info on what I meant by mouse flakiness.
	The program fills the screen with part numbers and the VT user can just
	select them by clicking on them.

	When the same program is run here on my PC through Xcursion
	via a terminal window to the VAX, the XY coordinates returned
	by the mouse are slightly skewed. The further I go from the
	0,0 origin, i.e. the further right and down, the further off
	the coords are so that clicking on one entry actually selects
	the one above or to the left of it.
3255.5JAMIN::OSMANEric Osman, dtn 226-7122Tue May 13 1997 12:255
That doesn't sound good.  Maybe the font size of the emulator is confusing
the mouse coordinates ?  What happens if you try a larger or smaller font ?

/Eric
3255.6Using ReGIS to output text workedPATE::COTEDave Cote, Hudson,MA.USA dtn 225-4166Fri May 16 1997 16:2210
	Thanks for pointing me in the right direction.

	What I didn't realize was that the text
	written to screen was not as ReGIS text. When I changed it to
	send it out using ReGIS, i.e. T(..)"text...", then everything
	fell into place. Now the mouse cursor seems to line up with the
	text consistently across platforms (the 2 I've tried so far).
	
	For now I can live without knowing if I'm on a VT vs an emulator.
								Thanks, Dave