*Bits 3..0 define Horizontal Sync Width. If 0 is programmed this gives a HSYNC width of 16.
==== R3 fine horizontal hard hardware scroll ====
If R3 is set to 5 instead of 6 or more, then the frame is shifted to the right on the CTM monitor with an offset of half a CRTC character. This is due to the effect of shortening the C-HSYNC produced by the [[Gate Array]].