Epson EPL-5500, Service Manual

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Print data and commands transmitted from the host computer via the parallel or optional interfaces
are read using the CPU interrupt process and stored in the DRAM input buffer. Data and commands
in the input buffer are processed by the CPU, which then stores the printing bitmap data (image
data) in the V (video) -RAM (image buffer) area of the DRAM. The size of the V-RAM depends on
the available DRAM size. A “PRINT OVERRUN” occurs when the V-RAM is so small that the CPU
cannot process data faster than it is transmitted to the engine controller board. If such an error
occurs, the user can increase the V-RAM using the printer setting “IMAGE OPTIMUM.”
The E05A91 transmits image data stored in the V-RAM to the E05A92. The E05A92 changes the
image data format from 32-bit parallel data to serial data, and stores it in the internal temporary
buffer. The temporary buffer has a capacity equivalent to several lines. This is controlled by the
E05A92, which synchronizes and transmits the temporary buffer’s data to the engine controller
board. The E05A92 then manipulates the printer data based on the BiRITech, EMGTech, and toner
saver settings.
Host Computer
Input Buffer
Dev elopm ent
V R A M Syst em Area
D R A M
Parallel/Ser ial
Convert er
RITech
EMGTech
Toner save Temporary
Buf f er
CPU
MB86933H
(IC1)
E05A91
(IC2)
E05A93
(IC4)
E05A92
(IC3)
Video
Figure 2-27. Data Flow Diagram
EPL-5500 Service Manual Operating Principles
Rev. B 2-19