HD64F3437TF16 Datasheet, PDF (359/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

Start
Host write
No
H'D1 command
received?
Yes
Wait for next byte
Host write
No
Data byte?
Yes
Write bit 1 of data byte
to DR bit of P8₁/GA₂₀
Figure 14.2 GA₂₀ Output
330