Laser
Manual
2.2.1.5
Interface Circuit
Figure 2-36 shows the parallel interface circuit block diagram. Data sent from the host computer is
latched within the
by the STROBE signaL
The
outputs the BUSY signal
automatically to stop the host computer from sending additional data. The CPU resets the BUSY
signal after reading the data from the
so that the printer is ready to receive more data from
the host computer.
DATA
Latch
STROBE
. . . . . ,
BUSY
. . . . .
Figure 2-36.
2.2.1.6 Optional
Interface
Parallel Interface Circuit
This printer supports an
Epson
Type-B
optional
interface, which is controlled by the
and
BIF
from
-
-
-
2.2.1.7
Video Interface
maps the
into a memory space different from the system memory. The CPU
transmits data from the V-RAM (in the system RAM) to the
using
converts the image data in the
from parallel to serial, synchronizes it, and then transmits it
to the engine controller circuit. In other words, the
is a temporary buffer used to transmit
the image data to the engine controller
This serial image data is the VIDEO
of the
video interface.
The signal line of the internal video interface circuit can be divided into four groups. The first
group (PRINT,
EPRDY, and
gives the status of either the video or engine controller
and indicates whether they are ready to communicate with each other or ready to start printing.
The second group
is the synchronizing signal for printing. The third group (VIDEO) is
the serial video data signal. The fourth group
and
is used to
transfer the commands (from the video controller) or the status (from the engine controller) for
printer mechanism control.
This printer has a standard
function. This function modifies the VIDEO signal with
on the main board.
2-24
Rev.
