AUTOEXEC

The AUTOEXEC.BAT file is a reference to original MS-DOS systems which would load settings from a file called CONFIG.SYS (which had to be located in the C:\ path), and then execute any commands found in the AUTOEXEC.BAT (also in the C:\ path). Commonly the AUTOEXEC.BAT file would define the system PATH, load any drivers, and launch Windows. Because DOSBox already emulates most of what a CONFIG.SYS, and AUTOEXEC.BAT would do, there isn't much need to define anything other than your mountable drives.

A Common AUTOEXEC.BAT

@ECHO OFF
MOUNT C C:\DOSGAMES
C:
CLS
@ECHO Starting MS-DOS 6.22...

This AUTOEXEC.BAT file mounts a C drive (pointed to the Local-Directory C:\DOSGAMES), changes to that drive (from Z:), Clears the Screen and prints the message

Starting MS-DOS 6.22...

(The message that MS-DOS printed immediately before loading the CONFIG.SYS and AUTOEXEC.BAT).