john1233@csd4.milw.wisc.edu (Thomas M Johnson) (11/10/87)
Well, I am about to purchase a PC clone. (to be exact a American
Research) and went to a friend's house to see it. (I'm buying it
from him used but still under warrenty). Well, we called this system
I'm on with his Avatex modem.
Everytime a CR was encountered, the screen would flash. He says that
even happens where he works and it is the terminal program.
I think it was PC-Talk.
Is this true? Is it the computer? Is it the modem?
Are there any terminal programs that don't flicker?
Tom
john1233@csd4.milw.wisc.edu
or
tommyj@lakesyscreps@silver.bacs.indiana.edu (11/13/87)
I'm not sure exactly what you mean by the terminal "flashes," but I'll guess that you mean what is usually called "snow." Snow is caused when there is a conflict in accessing the video controller. It can be programmed around, in that you can tell your program not to try to access the video while it's busy. Evidently, the terminal program you used didn't do this, and thus caused the snow. - - - - - - - - - Steve Creps on the VAX 8650 running Ultrix 2.0-1 at Indiana University. creps@silver.bacs.indiana.edu
dennis@rlgvax.UUCP (Dennis.Bednar) (11/13/87)
In article <15000049@silver>, creps@silver.bacs.indiana.edu writes: > > guess that you mean what is usually called "snow." Snow is caused when > there is a conflict in accessing the video controller. It can be programmed > around, in that you can tell your program not to try to access the > video while it's busy. Evidently, the terminal program you used didn't do The trick is to write to the video memory only when the hardware is doing a horizontal retrace or vertical retrace. Definition: A horiz retrace means that the video beam is sweeping back from the right side to the left side, preparing to paint the next odd or even row across your screen (left to right). Vertical retrace is when the video beam has reached the bottom right corner, and must go back to the top left corner of the screen. In both cases the video beam is off, not producing any color or information. When the video beam is painting a row left to right across a row, the memory is said to be "busy" (being fetched from by the 6845 video controller chip) - this is precisely is the time you want to avoid writing to the shared video memory. -- FullName: Dennis Bednar UUCP: {uunet|sundc}!rlgvax!dennis USMail: CCI; 11490 Commerce Park Dr.; Reston VA 22091 Telephone: +1 703 648 3300
em445@uiucuxf.cso.uiuc.edu (11/14/87)
I don't know about PC Talk, but I've NEVER came across a terminal program that flickered. If you want to make sure the problem isn't on your friend's computer, try running ProComm 2.4.2 on it. It DEFINITELY should not flicker...