Making a C64/C65 compatible computer
While fixing some other bugs in the MEGA65 today, I took the opportunity to implement an improved character mode for clearer text. The basic idea is that in V200 text mode, i.e., 25 rows of text mode, that each row of pixels is vertically duplicated, because the native video mode is still V400. In this mode, we can instead interlace which of the two C64-style charset ROM areas we pull the pixel data from, and display them on alternate lines. Note that this doesn't result in flashy interlace, because it is
NOTE: This post describes an optional feature that has been added. The default behaviour remains the same, and the MEGA65 will keep on booting up looking like it always did. This just creates a new option for programmers (and users) to make use of, to give their MEGA65 a different look.