Lexmark Printer manual Standard Protocol Data Transfer Sequence

8-15

Interfaces

•Controls data flow control with BUSY and ACKNLG* signals. Does not carry out data transfer by ignoring the BUSY or ACKNLG* signal. (The system can carry out data transfer to the printer only when the level of the BUSY signal is low and after confirming the ACKNLG* signal is high.)

•Uses standard transistor-transistor logic (TTL) levels for all interface control signals and input data. Interface conditions are based on TTL levels. All printer outputs are totem-pole TTL devices. All printer input/output (I/O) are devices with an internal pull-up resistor to 5 V. Rise and fall times of each signal must be less than 1,500 nanoseconds (ns) without slope reversal.

Standard Protocol Data Transfer Sequence

The following illustration shows the typical data transfer sequence on the parallel interface. See Table 8-2for typical parallel interface timings on the parallel interface.

DATA1-8

A B C

STROBE*

D

BUSY

ACK*

G F

E