Changes
CRTC
,/* Border conflict */
If R1=0 and HCC=0, we expect HBORDER to activate as HCC=R1 and we also expect HBORDER to deactivate as HCC=0. In this situation, all CRTCs activate HBORDER.
If R6=0 and VCC=0, we expect VBORDER to activate as VCC=R6 and we also expect VBORDER to deactivate as VCC=0. In this situation, all CRTCs activate VBORDER. On CRTC 1, even IBORDER SBORDER is activated. But on CRTCs 0/2, the first raster line shows an alternation of bytes of VBORDER and displayable characters.
To see the border bytes with your own eyes, type this BASIC line after reset: