Storage tube vector graphics terminals differ from refreshing vector graphics terminals in that the display stored whatever was drawn on it, and did not have to be refreshed many times a second in order to maintain a continuous image. One problem with refreshing vector displays is that they must continuously scan through the list of objects they are displaying, redrawing them as fast as possible, to maintain a visible image. Unlike a raster device where the path the electron beam follows is always the same, and always takes the same amount of time to follow, the path the electron beam follows on a vector display takes longer and longer as more objects are drawn. Therefore once a certain number of lines are being displayed, the display begins to flicker. Display list memory also limited the number of line segments that could be viewed simultaneously.
To get around these problems, the storage tube was used. In a storage tube, there are actually two electron guns. One draws lines on the screen, the other bathes the entire display in electrons at a lower intesity. This second beam keeps any phospher that has been activated continuously illuminated. Thus when a line has been drawn with the first beam, the second beam keeps it lit. Therefore the terminal only has to draw a line once, and it remains on the screen. There is no flicker, and no problem with having lots and lots of objects on the screen at once.
The trade-off is that it cannot erase anything except by clearing the entire screen. Therefore you cannot have motion or any sort of animation on the screen. Later displays got around this by using a lower-intensity mode for drawing which was not intense enough for the phospher to remain lit by the second beam. When it wanted to draw a permenant line, it still could, by increasing the intensity of the drawing beam for that one object. Later tektronics terminals did this. The early models did not, except for the special cases of the cursor, and displaying cross-hairs to let the user select a point.
Some more Links:
This Link describes in detail about the console.
Shows the Computer with a screen Image, in a black and white picture.
This Link says it was the Tectronix 4050 that was used in BSG.
I have all the episodes on tape. When watching the episodes, the 4051 looks like the real deal.
Because Most of the web pages show the computer off,
the only Page that shows an image
that comes close is this link:
This is not the 4051 but it is a decent picture of These type of Displays. It is a color picture. Notice that familiar faint glow of the screen, it looks like the vector images on BSG.
The only problem is this computer console is a very rare item. I could not find it on ebay. If it ever shows up, I want this little gem for my collection. I hope that you enjoy this Webpage, I will try to update in the months ahead.