Brother DCP-4020C - Manual (Page 78)

USING THE DCP AS A PRINTER 7 - 3
Simultaneous printing
Your DCP can print from your computer while scanning a document
into the computer. However, when the DCP is copying, it pauses the
PC printing operation, and resumes when copying is complete.
Clearing data from the memory
If the LCD shows DATA REMAINS , you can clear the data that is left
in the printer memory by pressing Stop/Exit .
Checking the Print Quality
If you want to check the print quality and find out how to improve it,
See How to improve print quality on page 15-8.