Interface; 8-Bit Parallel Interface - Epson LQ-1050 Technical Manual

2.3.2 Interface

This printer has both 8-bit parallel interface and RS-232C serial interface.

2.3.2.1 8-Bit Parallel Interface

Operating Principle
Figure 2-27 shows the 8-bit parallel interface data transmission timing. Data is transferred between
a host computer and the printer using the following sequence:
BUSY
DATA
STROBE
—
Fig. 2-27. Data Transmission Timing of 8-bit Parallel Interface
a) First, the host computer confirms that the BUSY signal from the printer is low or that the
signal from the printer is high. When the BUSY signal is low, the printer is ready to receive data.
When it is high, the printer
data. Therefore, the host computer does not transfer data until the BUSY signal changes from high
to low. (Some host computers confirm the states of both the BUSY and
confirm the state of either the BUSY or
After the host computer has confirmed that the BUSY signal is low, it transmits data (8 bits per ward)
b)
in parallel on the data bus
pulse.
After receiving data from the host computer, the printer sets the BUSY signal high to inform the
c)
host computer that the printer is processing data and can not receive data.
After completing the data processing, the printer sets the
d)
computer to transfer data again. The printer sets the BUSY signal to low aooroximately 5
setting the
5 informing that the host computer that the printer is ready to receive data.
Operation
This circuit employs a general-purpose 8-bit parallel interface
pin assignments of the
can not receive data from the host computer since the printer is processing
and the printer reads the data at the falling edce of the STROBE
signal to low, then the printer sets the
10P.
signal.)
2-27
signals, and others
signal to low, allowing the host
signal to high approximately
10P (5A). Table 2-11 lists the
REV.-A
after