Used by the routine at E1BE.

this routine is used to open a logical file. Once the logical file is set up it can be used for input/output operations. Most of the I/O KERNAL routines call on this routine to create the logical files to operate on. No arguments need to be set up to use this routine, but both the SETLFS, FFBA, and SETNAM, FFBD, KERNAL routines must be called before using this routine.