[grymoire1]

The first BASIC I used (1976?) was designed to run in a machine with 4K of memory (a 16-bit minicomputer). There was no operating system, nor no disk. You installed the program using a paper tape reader.

At this time, the best "full screen" editor we could find was actually a very expensive CRT terminal that did all of the editing in the terminal's memory. It required an operating system and a disk. The program read 1K of data into terminal memory, and using keys built into the terminal, you could move the cursor around and cut and paste. When done, it write the memory into a file, and read the next 1K of data.

The computer it was attached to had an editor like TECO (DEC), NSPEED (Data General), or EX (AT&T Unix). These were editors designed to be used on dumb terminals or even hard copy terminals (Like a TeleType ASR33, Silent 700, or DECWriter).

A full screen editor would need an operating system with support for files (Floppy or the outrageously expensive hard disk), and enough memory to support a program on top of the operating system, on top of the program you are editing.