when was memory "above" the terminal screen invented?

[Brent Hilpert]

On 2020-Dec-13, at 6:37 PM, Stan Sieler via cctalk wrote:
> ...
> 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.)


If it fits your definitions, you might look into the Teletype Model 40 if more info to that below can be found.

On pdf.pg.60 of this article:
	http://www.bitsavers.org/pdf/datapro/alphanumeric_terminals/Datapro_C25-010_197904.pdf
the Model 40 is shown with "Paging: Opt. 2/3 pages" and "First production delivery: 10/73"