When R3l decreases by 1 (and if >2), the screen is shifted to the right by 8 mode2 pixels.
The shift is not instantaneous but follows a logarithmic attenuation across several raster lines. This property can be used to get even finer horizontal control by modifying R2/R3 on each raster line. [[Longshot]] demonstrated [https://youtu.be/1q7RQykZoKY 1-pixel horizontal hardware scroll] with one-pixel precision in mode 1 mode1 on all CRTCs.
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