Video Interface - Epson C11C605001 - DFX 9000 B/W Dot-matrix Printer Service Manual

2.2.1.10 Video Interface

The ASIC E05A92 maps the SRAM into a memory space different from the system memory. The
CPU transmits data from the V-RAM (in the system RAM) to the W using the ASIC E05A92.
The ASIC cell converts the image data in the SRAM from parallel to serial, synchronizes it, and
then transmits it to the engine controller board. In other words, the SRAM is a temporary buffer
used to transmit the image data to the engine controller board. This serial image data is called the
VIDEO signal of video interface.
The signal line of the internal video interface arcuit (the C135 MAIN board and engine controller
board) can be broadly divided into four groups. The first group (PRINT, CPRDY, RDY, and PRD)
gives the status of either the video controller or engine amtmller and indicates whether they are
ready to communicate with each other or ready to start the printing
(TOP, BD) is the synchronizing signal for the printing operation. The third group (VIDEO) is the
serial video data signal. The fourth group (CMD, CCLK, CBSY, and EBSY) is used to transfer the
commands (from the video controller) or the status (from the engine controller) for printer
mechanism control. Except for VIDEO, PRINT, TOP, and BD, all signals are controlled by ASIC
E05A93.
This printer has BiRITech and EMGTech functions standard. These functions modify the VIDEO
signal with the ASIC E05A92.
2-30
operation. The group
second
Rev. A