Chapter 9 Precautions for use

Precautions for use are as follows.

● VDP1 general

• For normal, high resolution, HDTV, and double-dense interlacing, frame buffer rotation reading is prohibited. [ reference ]

• The CPU can only access the drawing framebuffer. [ reference ]

● System register

• DMA access to system registers is prohibited. Please be sure to use Word Access. [ reference ]

• After turning on the power, be sure to set the system registers. [ reference ]

• Be sure to set unused bits of system registers to 0. [ reference ]

• When reading the frame buffer rotationally, be sure to set DIE = 0. Rotational reading with double-dense interlacing is prohibited. [ reference ]

• Please note that an undefined surface will be displayed in the first frame immediately after changing the DIE bit. [ reference ]

• When changing TVM bits, it is necessary to mask the frame buffer. When changing, one frame of the irregular surface will be displayed. [ reference ]

• For double-dense interlacing, set FCM=0 and FCT=0. Field switching is only possible at 1/60 seconds. [ reference ]

• Erase write area settings are (upper left coordinates XA)＜ Please set so that (lower right coordinate XC) and (upper left coordinate YA) ≦ (lower right coordinate YC). [ reference ]

● Command

• Relative coordinates must be set after the power is turned on. [ reference ]

• The range that can be set for clipping coordinates is from (0, 0) to (1023, 511). [ reference ]

• The range of clipping coordinates is (upper left coordinate XA) ≦ (lower right coordinate XC) and (upper left coordinate YA) ≦ (lower right coordinate YC). [ reference ]

• For clipping, set appropriate values according to the screen mode set with the TVM bit. [ reference ]

• Be sure to set the user clipping area inside the system clipping area. Collinearity can be set. [ reference ]

• The upper left coordinate of the system clipping area is fixed to (0, 0) by hardware. [ reference ]

• Set unused bits in the words you are using to 0 in the command table. [ reference ]

• Calls (calls, jump calls, skip calls) within command subroutines are prohibited. [ reference ]

• Returns (returns, jump returns, skip returns) within the command main routine are prohibited. [ reference ]

• Zoom point values can only be 0H, 5H, 6H, 7H, 9H, AH(10), BH(11), DH(13), EH(14), FH(15). Any other settings are prohibited. [ reference ]

• When HSS=1, the end code of the original picture is ignored regardless of whether the sprite is enlarged or reduced. [ reference ]

• Set the lower 2 bits of CMDLINK to 00. [ reference ]

• Set the lower two bits of the lookup table to 00. [ reference ]

• When setting the color bank, set the lower 4 bits of the color bank data to 0000. [ reference ]

• When using non-texture, set ECD=1, SPD=1, and color mode=0. [ reference ]

• When performing color calculations without texture, set RGB data (8000H or higher) to the non-texture color. [ reference ]

• When setting to RGB mode and using 7FFFH data for the original picture, please set ECD = 0. [ reference ]

• When setting to RGB mode and using data of 0000H for the original picture, please set SPD = 0. [ reference ]

• When set to RGB mode, setting the frame buffer to 8 bits/pixel is prohibited. The only color modes that allow 8 bits/pixel are modes 0, 1, 2, 3, and 4. [ reference ]

• When setting the frame buffer to 8 bits/pixel, set the color calculation mode to 0. Only replacement is possible. Other color operations are prohibited. [ reference ]

• When the frame buffer is set to 8 bits/pixel, the upper 8 bits of non-textured colors are ignored. At this time, use of RGB data is prohibited. [ reference ]

• Do not set the MSB on bit (MON) to 1 when the frame buffer is set to 8 bits/pixel. [ reference ]

• When the MSB on bit (MON) is set to 1, set the color calculation mode to 0. [ reference ]

• Store the command table at address 000000H of VRAM. [ reference ]