I often code directly on the machine control, including single blocking a running program and adding a line while the program is paused.

Editor on older CNC machines usually doesn't even do lowercase and often has limited alphabet keys. Think '80s green or amber screen.

A machinist's coding workflow can be real fucky. I go from CAM which is like a highly complex visual programming IDE to notepad. If I'm being fancy I use notepad++ for syntax highlights and diff'ing.