Star Micronics Star SCP700 Series Programmer's Manual page 21

Buffer full cancellation in DTR mode (the following is an example in the
Combination mode).
A) Buffer set to "big size" (4K-bytes) (set with dip switch 2-3)
Data buffer
Full
Near Full
Remainder
256 bytes
DTR "MARK"
When available space drops below 256 bytes, DTR is set to "MARK." When
data in the buffer drops below 256 bytes, DTR is set to "SPACE."
B) Buffer set to "small size" (45-bytes) (set with dip switch 2-3)
Data buffer
Full Near Full
Remainder
16 bytes
DTR "MARK"
When available space drops below 16 bytes, DTR is set to "MARK." When data
in the buffer drops below 16 bytes, DTR is set to "SPACE."
Near Empty
256 bytes
DTR "SPACE"
Near Empty
16 bytes
DTR "SPACE"
17
Empty
Empty