Hitachi HD64411 Q2, User Manual

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Section 1 Overview of Q2 (Quick 2D Graphics Renderer)
1 . 1 Q2 Overview
The Q2 (Quick 2D Graphics Renderer) has been developed as the first product in the SuperH RISC
engine graphics accelerator “Quick” series (Q series). The Q2 is a 2D graphics renderer LSI for
minimum system configuration use, based on the concepts of simplicity, realtime operation, and
upgradability.
The Q2 is positioned as a SuperH RISC engine (abbreviated to “SuperH” below) chip set.
Operations for which there is a possibility of the algorithm being changed, such as geometric
operations (of which coordinate conversion is a typical example), are performed by the SuperH,
while drawing (rendering), which would lower the efficiency of the SuperH bus utilization, is
performed by the Q2. This provides the flexibility required for updating algorithms while also
improving bus utilization.
In addition, the hardware configuration has been simplified, with the inclusion of a built-in CPU
interface circuit, display circuit, and memory interface circuit, functions previously supported by
external circuitry.
Moreover, first-time use of UGM (unified graphics memory) enables frame buffer areas, font
patterns, line patterns, and other data to be located in a single memory (one 4 MB memory in the
minimum configuration).
The use of a double-buffering architecture in which the drawing buffer and display buffer allocated
to the UGM are switched by frame or field, together with the use of EDO page mode DRAM for
the UGM, enables display processing and high-speed drawing processing to be executed in real
time.
Figure 1-1 shows an overview of the Q2 system.