More interestingly, the same mode was used WITHOUT the
half-block trick
for some truly creative graphics:
You could do a similar trick (I think it's similar anyway) on the CoCo 1
and 2 in the Semigraphics modes. Each byte of video memory corresponded
to 1 charaxcter cell width by 1,2,4, etc scan lines. You were _supposed_
to put bytes with the high bit set there, in which case the lower bits
determined the colour and on/of state of the 2 halves of the cell. You
could actually put any character there, whereupon the appropriate dots
from that scan line of that character would be
displayed. You could, for
example, have the uppper and lower halves of the
character cell coming
from different characters.
Pity the CoCo 3 didn't support the semigraphics modes.
-tony