Oki ML1120 Technical Reference Manual page 31

NOTE
Characters to be printed according to the parity error
indication code (40)H will differ depending on the setting of
the printer character set. Refer to the printer User's Guide.
Ready/Busy protocol
Block format
Error indication
Busy state indication
Timing chart
RD
8K
Threshold of the
characters in 512
the buffer
0
SSD
Technical Reference Guide – Interface specifications > 31
Free
The parity error indication is printed as character
40(H).
The busy signal turns on (becomes Busy) when the
space in the interface buffer has become less than
256 bytes. The busy signal turns off (becomes
Ready) after 200 ms or 1 second has passed if 256
bytes have recovered within 200 ms or 1 second. If
the recovery time exceeds 200 ms or 1 second, the
busy signal turns off (becomes Ready) immediately
after the recovery has occurred.
DATA 1
ON (BUSY)
OFF (READY
200 ms or 1 second minimum
DATA 2