pfarrell@anselm.UUCP (Gladiator Supreme.) (04/26/88)
Recently I had asked if a point could be erased from a TEK4014 screen. I recieved an overwhelming response of NO!!!!! It seems because the 4014 is a DVST that is does not use rasters, and thus there is no memory inside to fu-- with and erase points. I wrote back to many saying WRONG! Well it is I who might be wrong. The program 2020 does seem to erase points, but it blinks while doing it. But it also blinks while drawing. So maybe it is erasing and redrawing at an incredible rate. Anyway, don't take my word from it, because I am far from an expert on TEK internals. -Gladiator
sas1@sphinx.uchicago.edu (Stuart Schmukler) (05/05/88)
In article <172@anselm.UUCP> pfarrell@anselm.UUCP (Gladiator Supreme.) writes: >Recently I had asked if a point could be erased from a TEK4014 screen. >I recieved an overwhelming response of NO!!!!! ... >Well it is I who might be wrong. The program 2020 does seem to erase >points, but it blinks while doing it. But it also blinks while drawing. >So maybe it is erasing and redrawing at an incredible rate. Anyway, >don't take my word from it, because I am far from an expert on TEK >internals. I think that your program is using an option of the 4014 that allowed you to modulate the beam current. Below some thresh-hold the you "see" the beam, but it does not "store". (I think I have the terms correct.) So, the flashing you see is the beam refrashing the object. I believe this is correct, but since I do not have a real Tek 4014 manual here I cannot be sure. The VT640 (Digital Engineering's raster emulation of a 4014) manual I have mentions "data level" commands: <ESC>/Pd Where P is 0 dots turned on 1 dots turned off 2 dot toggled/complemented I am sure that these are NOT the same commands that you would use to put a real 4014 into "no-write" mode. But, you can do useful things in any case. I wrote an interactive spectrum editor that used these features of the VT640 to move a number of markers on the screen. This and the VT640's other "feature", a visible VT100 screen under the graphics screen allowed the user to do a number of analyses without having to redraw the screen. A big win when it could take O(1 min) to redraw the when displaying 2048 or more points. I'll stop now -- its late -- old porgrammers need their rest. SaS PS: I know there ways to speed up the display of that many points on a 640x480 screen, but I never had the time to get them working. This method has the added advantage of always having something on the screen for the user to look at. (So they do not get nervous and mess the program up.)