Several years ago PC Magazine described a patch for DOS3.1 which allowed
you to modify COMMAND.COM so that the screen always cleared to the colors
of your choice.  Recently I went through the pain of switching to DOS3.3, and
I wanted to do the same thing.  Bill Stewart was kind enough to leave
a message on the Midnight Express BBS to tell me how to do it.  He also
provided the information on how to do the same thing for all the versions
of DOS. Here are the patch locations in COMMAND.COM to set colors on
startup of your PC.
 
2.0 - 2346
2.1 - 2359
3.0 - 2428
3.1 - 2642
3.2 - 282E (27BE for MS-DOS 3.20)
3.3 - 2BAD
 
With this information, type DEBUG COMMAND.COM (on a BACKUP copy of your
COMMAND.COM file), then type "E nnnn xy", where "nnnn" is one of the
addresses above, and xy is your hexadecimal background/foreground color
combination.  Type the above E command without the quotes, of course. 
Type Q to quit DEBUG.  For example, to patch DOS 3.1's screen colors to
white on blue, do the following:
 
DEBUG COMMAND.COM
E 2642 17
W
Q
 
The W command writes the change back to disk.  You have to reboot (and
thus load COMMAND.COM again) to see the change.

If you have troubles, Bill Stewart can be reached on the DOS Power User's
conference on the Midnight Express BBS (505)-836-9576.

Bill Baer
Albuquerque, NM
2/28/89