4.3.1 Noscreen Mode
  Noscreen mode is the default, line-oriented mode of display-
  ing input and output. To get into noscreen mode from screen
  mode, enter SET MODE NOSCREEN. See the sample de-
  bugging session in Section 4.7 for a demonstration of noscreen
  mode.

  In noscreen mode, you can use the TYPE command to dis-
  play one or more source lines. For example, the following
  command displays line 3 of the module that is currently
  executing:
  DBG> TYPE 3
  3: EXTERNAL SUB TRIPLE &
  DBG>

  The display of source lines is independent of program execu-
  tion. You can use the TYPE command to display source code
  from a module other than the one currently executing. In
  that case, you need to use a directory specification to spec-
  ify the module. For example, the following command displays
  lines 16 to 21 of module TEST:
  DBG> TYPE TEST\16:21