Epson TM-T20 Technical Reference Manual page 60

When the printer finishes printing the printer status, the following message is printed and
the Paper LED flashes. (The printer is now in the self-test wait mode.):
3
Press the Feed button to start the test print (less than 1 second).
The printer starts test printing. (A rolling pattern is printed using only the resident
character set.)
If you select "Mode Selection," the printer goes to
(page
Setting Mode" (page
After the test printing has finished, the printer prints the following message, and then the
printer is initialized and returned to the normal mode.
60
"Select Modes by pressing Feed button.
Continue SELF-TEST: Less than 1 second
Mode Selection:
62), "Receipt Enhancement Information Print Mode" (page
64).
"*** completed***"
1 second or more"
"NV Graphics Information Print Mode"
63), or "Memory Switch