The COMMAND.COM filename was also used by Disk Control Program [de] (DCP), an MS-DOS derivative by the former East German VEB Robotron.

The second is batch mode, which executes a predefined sequence of commands stored as a text file with the .BAT extension.

[4][3] On exit, all external commands submit a return code (a value between 0 and 255) to the calling program.

[citation needed] Generally, the command line length in interactive mode is limited to 126 characters.

[11][12][13] In MS-DOS 6.22, the command line length in interactive mode is limited to 127 characters.

You cannot use any of the redirection characters [<>|], or the blank, tab, comma, or equal sign as the command separator.

[...][...] all MS-DOS versions prior to Windows 95 [...] used a COM style COMMAND.COM file which has a special signature at the start of the file [...] queried by the MS-DOS BIOS before it loads the shell, but not by the DR-DOS BIOS [...] COMMAND.COM would [...] check that it is running on the "correct" DOS version, so if you would load their COMMAND.COM under DR-DOS, you would receive a "Bad version" error message and their COMMAND.COM would exit, so DR-DOS would [...] display an error message "Bad or missing command interpreter" (if DR-DOS was trying to load the SHELL= command processor after having finished CONFIG.SYS processing).

Now, things have changed since MS-DOS 7.0 [...] COMMAND.COM has internally become an EXE style file, so there is no magic [...] signature [...] to check [...] thus no way for DR-DOS to rule out an incompatible COMMAND.COM.