Browse Prior Art Database

Vector Generator Rate Control using Variable Address Resolution

IP.com Disclosure Number: IPCOM000049925D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Beausoleil, WF: AUTHOR [+2]

Abstract

Computer graphic display devices using directed-beam cathode ray tubes as the display medium often are used in a variety of applications having different requirements. Two requirements which are often in conflict are display resolution and dynamic data capacity; i.e., the desirability of precision in a display usually must be balanced against the desirability of speed, which is the primary determinant of refreshed display capacity. Circuitry which is both very fast and very precise tends to be very expensive, if /t can be built at all.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Vector Generator Rate Control using Variable Address Resolution

Computer graphic display devices using directed-beam cathode ray tubes as the display medium often are used in a variety of applications having different requirements. Two requirements which are often in conflict are display resolution and dynamic data capacity; i.e., the desirability of precision in a display usually must be balanced against the desirability of speed, which is the primary determinant of refreshed display capacity. Circuitry which is both very fast and very precise tends to be very expensive, if /t can be built at all.

A classic example of such conflicting speed vs. precision requirements is found in display stations which use a direct-view storage tube (DVST), which is capable of displaying both stored and dynamic vectors. Stored vectors must be written at a relatively slow rate (on the order of 150 meters/second) to permit reliable operation of the storage mechanism. Dynamic (refreshed) vectors may be written more rapidly, typically at eight or ten times the stored writing rate. However, these dynamic vectors must be refreshed at 30-50 frames per second to remain visible and flicker-free, so writing speed is the major factor in determining how much dynamic data can be displayed without flicker.

It is generally true that refreshed displays provide less precision (resolution) than stored displays, so most applications that require large quantities of refreshed data have adapted to less stringent resolution requirements. On the other hand, a major advantage of stored displays, such as the DVST, is the large volume of data which may be displayed without flicker. Such large volumes almost always require high resolution to permit the user to distinguish objects. Thus, stored vectors usually need to be more precise than refreshed vectors.

The following technique provides a means of adapting a conventional high- resolution vector generator to permit much faster ve...