Chapter 4 (j) - HIMEM.SYS is quiet by default.
 
By default, the MS-DOS 6 version of HIMEM.SYS loads without displaying any status messages. 
To instruct Himem to display status messages (for example, A20 line information) as well as warning 
and error messages, edit your CONFIG.SYS file and add the /verbose (/v) switch to the device command
for HIMEM.SYS. (You can also display startup information by pressing the ALT key while your 
computer is starting.)
If Himem encounters an error during initialization, it switches to verbose mode and displays the error 
message and all remaining startup information.

 