when was memory "above" the terminal screen invented?

On Dec 13, 2020, at 9:37 PM, Stan Sieler via cctalk <cctalk at classiccmp.org> wrote: Hi, First, apologies if I asked this years ago (I've searched my archives, no hits :) When was the concept of memory "above" the screen invented for terminals? I.e., previously displayed data that had scrolled up and off the screen ... but could be retrieved (usually by scrolling down). (Sometimes called "scrollback", or "offscreen memory".) (BTW, I'm talking about terminal-local memory, not a scrollback implemented by the computer to which the terminal is connected.) The HP 2640A, 1974, had (IIRC) several pages of memory available ... the user could scroll backwards and see what had been on the screen before it scrolled off (as long as it hadn't been lost by having too much subsequent output). I suspect the DEV VT100, 1978, had it, but I can't find definitive proof online (sure, I can find VT102 emulators that have scrollback, but reading an old VT102 manual doesn't make it clear that it has it.)