Atari XL

164
The Atari XL Handbook
of the normal 8. The number of lines on the screen
is reduced to 19.
N ow try typing some lower case characters; you
will observe that some of them appear slightly
different from normal - they have the pixel
normally in the top row of the character displayed
on the bottom. This is because in this mode,
ANTIC takes character data from memory in a
slightly different order from usual, but only for
characters with ASCII codes between 96 and 128.
You may be wondering what use there is for this -
it allows you to create a more legible character set,
in which characters like g, y and j can have
descenders (the part of the character that normally
appears below the line of the text). This involves
reprogramming the character set as described in
Chapter If you want to try this you should be
aware that the data in the top two rows of the
character grid is displayed in the bottom two rows
on the screen, so to create a letter p with a
descender, your character grid should look like
this:
The Character p as Stored in
Memory
ANTIC will rearrange the data so that when
displayed, the character appears like this: