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Work coordinates (2-dimensional coordinate system)
These are the coordinates for managing graphics used when rendering attribute work
specification is performed. Work coordinates are managed by the Q2 so that there is a 1-to-1
correspondence for each rendering coordinate pixel. Clipping processing is also handled in
the same way as for rendering coordinates.
Binary source coordinates (1-dimensional coordinate system)
These are coordinates for storing character patterns and line patterns. Character patterns and
line patterns are stored in order from any address in the UGM, and pattern sizes are managed
with a 2-dimensional coordinate system using command parameters TDX and TDY.
• Rendering reference data
In drawing that references the transfer source, the referenced data format may be multi-valued
source data or binary source data, defined as individual multi-valued source coordinates and
binary source coordinates.
In drawing that does not reference the transfer source, specified color data may be referenced.
With a POLYGON4 type command, work data may be referenced.
• Rendering attributes
Seven kinds of attribute specifications can be made: work (WORK), clipping (CLIP),
transparent (TRNS), source style (STYL), net drawing (NET), source half (HALF), and
even/odd select (EOS). The attributes that can be specified depend on the command.
4 . 2
Command Fetching
The Q2 carries out drawing operations while performing fetches from the display list stored in the
UGM. The display list consist of a number of linked Q2 drawing commands.
The Q2 performs sequential fetches in low-to-high address order, starting at the address set in the
display list start address register (DLSAR). The fetch address can be changed midway, using a
JUMP or GOSUB command. Q2 fetching can be terminated by placing a TRAP command at the
end of the display list.
The Q2 has a 32-byte dedicated command buffer, and an equivalent area of the UGM is accessed at
one time. When processing of the commands in this buffer is completed, another command fetch is
performed.
If the commands include a JUMP, GOSUB, or other command that changes the flow, the Q2
continues its fetch operation from the address indicated by that command.
Figure 4-1 shows an example of the display list.
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