Hitachi HD64411 Q2 User Manual page 43

Auto Display Change Mode: In auto display change mode, display frame switching has
priority. If drawing is in progress when the frame is switched, drawing is aborted midway through
that display list. It is therefore essential for drawing to be finished before the arrival of a VSYNC
synchronization pulse. An outline of operation in this mode is shown in figure 3-9.
VSYNC
(non-interlace
operation)
Q2 operation
Interrupt
CPU operation
handling
F0: Frame buffer 0
F1: Frame buffer 1
VBK flag: Vertical blanking flag (bit 11 of status register (SR))
Figure 3-9
Auto Rendering Mode: In auto rendering mode, display switching is not performed until
drawing ends. If drawing does not end within one frame, it is continued without interruption. An
outline of operation in this mode is shown in figure 3-10.
36
1st frame
Display screen: F0
Drawing destination: F1
Drawing to F1 aborted
F0 display list transfer
Operation in Auto Display Change Mode
2nd frame
Display screen: F1
Drawing destination: F0
Interrupt
handling
F1 display list transfer