Re: Talking of 1-2-3
Basically you are talking about the difference between synchronous (or to IBM bisynchronous) terminals and asynch. ASCII/EBCDIC has nothing to do with it.
It is quite possible to have an asynchronous terminal working in "forms mode" where you did local form editing and then hit "transmit" to send the data to the host.
Asynch terminals would be switchable between the two modes, synchronous ones, not.