Digital Equipment DECcolorwriter 1000, Руководство по обслуживанию

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Service Manual
5-17
Theory of Operation
5
DECcolorwriter 1000 image processor
Image rendering technology
The image processor board handles PostScript data sent from a host computer and
transforms it into a format suitable for the print engine. The hardware/software structure
that performs this function is called a graphics pipeline. The graphics pipeline is
composed of five basic parts.
n
The I/O serializer handles the communication and protocol with the host
computers connected to the serial, parallel, Ethernet, and LocalTalk ports as
well as the SCSI port. A special portion of the I/O serializer is dedicated to
handling the multi-layered AppleTalk protocol.
n
The PostScript data received through the I/O serializer is routed to the
PostScript interpreter. The PostScript interpreter generates display lists
which describe objects and text fonts as they are to appear on the printed
page. As needed, the PostScript interpreter reads font data stored in ROMs on
the image processor board. The PostScript interpreter also handles errors it
encounters in the PostScript data.
n
The PostScript interpreter's display list is, in turn, routed to the rasterizer.
The rasterizer converts the objects and fonts into a bitmapped image
composed of color planes. Color planes are bitmaps of the primary colors
cyan, magenta and yellow that make up the image.
n
The engine driver outputs the color bitmaps to the print engine. It handles the
data transfer buffering and basic input/output functions.