To control the MCI debugging output and the output from OutputDebugStr, set the MCI and DebugOutput keynames in the [mmsystem] section of SYSTEM.INI to the values shown in the following table:
| Setting | Description |
| DebugOutput=0 | OutputDebugStr and MCI debugging output is not displayed. |
| DebugOutput=1 | OutputDebugStr and MCI debugging output is sent to the COM1 port. |
| DebugOutput=2 | OutputDebugStr and MCI debugging output is sent to a secondary monochrome display adapter. |
| MCI=0 | MCI debugging output is disabled. |
| MCI=1 | Normal MCI debugging output is enabled. Normal MCI debugging output reports a string representation of each MCI command. |
| MCI=2 | Extended MCI debugging output is enabled. Extended MCI debugging output reports the length of time that a command took to complete, along with a string representation of the command. |
If debugging output is directed to a secondary monochrome display adapter where CVW is running, the debugging output appears in the CVW command window.
Note:
Fatal-exit reports are always directed to the AUX device (usually assigned to COM1), and cannot be disabled. Only MCI debugging output and output from OutputDebugStr can be disabled and directed to either COM1 or a secondary monochrome display adapter.