art@ACC.ARPA.UUCP (05/16/86)
>>VMS only allows one image to execute at a time from within a single >>process. Thus if you want the image to continue processing after invoking >>another image, the second image must run in either a subprocess or a detached >>process. > >Question. How does DCL do it, then? _It_ succeeds in running an image in >the same process as itself without needing to spawn or start a detached >process. DCL is special, in that the image activator maps CLIs into P1 space of a process. LOGINOUT creates the initial process with just DCL in the process. When DCL runs an image, the image is mapped into P0 space of the process without destroying DCL. This allows the image to call back to DCL for command prompting. This also allows an image to be interrupted back to DCL with ^Y and later restarted with CONTINUE (unless another image is activated). It may be possible to have an image which allocates virtual memory, loads *position independent* code into it and executes it. <Art@ACC.ARPA> ------