Oki PT390 Manuel D'utilisation page 84

Then, press and hold down the FEED switch for one second or longer to
accept the selection.
The printer prints the following when you accept the selection of "PRINT
COLOR":
7. Select "TWO" as your option.
Press the FEED switch briefly (one second or less) until "TWO" is reached.
Then, press and hold down the FEED switch for one second or longer to
accept the selection.
PRINT COLOR MONO
PRINT COLOR TWO
PRINT COLOR MONO
SELECTION ITEM
PRINT COLOR TWO
PRINT COLOR MONO
PRINT COLOR TWO
PRINT COLOR MONO
SELECTION ITEM
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