Roll mode was frequently on DSOs but does not seem to be on some products today. What was the advantage of roll mode+ and what function or technique has replaced it?

Roll mode was frequently on DSOs but does not seem to be on some products today. What was the advantage of roll mode+ and what function or technique has replaced it?

Roll mode provides an instant display response at very slow sweep speeds. Without it, the acquisition must complete before the display will update. Some instruments have a Scan mode that works similarly but starts at the left side of the display rather than the right. In some high bandwidth instruments roll mode will be so seldom used that it is not cost-effective to provide it.