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You can describe BCD using hexadecimal notation. You can describe binary data using decimal notation. Notation is orthogonal to storage format. I don't think s

You can describe BCD using hexadecimal notation. You can describe binary data using decimal notation. Notation is orthogonal to storage format. I don't think storing bitmap graphics in ROM as BCD was ever really a thing. If you had reserved space for 4 BPP, would you really say "nah I don't need 16 colours, 10 is enough for me".

megameter 6y ago
On the other hand, bitmaps stored in planar form were supported by many hardware systems in the time frame of the article(the Amiga, for one, used a planar scheme). This did allow for bitdepths other than powers of 2 with the requirement of resolutions being multiples of a byte or word(so, 8 or 16). This is particularly useful when considering overall asset storage constraints - 8 colors(3bpp) is often plenty for small sprites.