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■ Reduction enable register

The reduction enable register controls the horizontal reduction display. This is a write-only 16-bit register located at 180098H. The value is cleared to 0 after power-on or reset, so be sure to set it.

Zoom enable bit : Zoom quarter / half bit (N1ZMQT, N1ZMHF, N0ZMQT, N0ZMHF)

Specify the maximum horizontal reduction possible range of each normal scroll screen.

N0ZMHF 180098H Bit 0 For NBG0
N0ZMQT 180098H Bit 1 For NBG0
N1ZMHF 180098H Bit 8 For NBG1
N1ZMQT 180098H Bit 9 For NBG1

NxZMQT NxZMHF Horizontal reduction display Restrictions
0 0 No None
0 1 Up to 1/2 16 or 256 colors
Can only be set in case of
1 0 1/4 possible When the number of character colors is 16 Can only be set
1 1 Up to 1/4 possible When the number of character colors is 16 Can only be set
[Note] 0 or 1 is entered in x of the bit name.

For reduction to 1/2, set the number of character colors (bitmap pattern colors) on the corresponding screen to 16 or 256 colors. Set the reduction to 1/4 to 16 colors.
∙ Make sure that the horizontal coordinate increment does not exceed the setting range of these bits.

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