Specifications

ZPL Commands
^CO
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45541L-004 Rev. A ZPL II Programming Guide 9/15/06
^CO
Cache On
Description The ^CO command is used to change the size of the character cache. By
definition, a character cache (referred to as cache) is a portion of the DRAM reserved for
storing scalable characters. All printers have a default 40K cache that is always turned on. The
maximum single character size that can be stored, without changing the size of the cache, is
450 dots by 450 dots.
There are two types of fonts used in Zebra printers: bitmapped and scalable. Letters, numbers,
and symbols in a bitmapped font have a fixed size (for example: 10 points, 12 points, 14
points). By comparison, scalable fonts are not fixed in size.
Because their size is fixed, bitmapped fonts can be moved quickly to the label. In contrast,
scalable fonts are much slower because each character is built on an as-needed basis before it
is moved to the label. By storing scaled characters in a cache, they can be recalled at a much
faster speed.
The number of characters that can be stored in the cache depends on two factors: the size of the
cache (memory) and the size of the character (in points) being saved. The larger the point size,
the more space in the cache it uses. The default cache stores every scalable character that is
requested for use on a label. If the same character, with the same rotation and size is used
again, it is quickly retrieved from cache.
It is possible that after a while the print cache could become full. Once the cache is full, space
for new characters is obtained by eliminating an existing character from the print cache.
Existing characters are eliminated by determining how often they have been used. This is done
automatically. For example, a 28-point Q that was used only once would be a good candidate
for elimination from the cache.
Maximum size of a single print cache character is 1500 dots by 1500 dots. This would require
a cache of 274K.
When the cache is too small for the desired style, smaller characters might appear but larger
characters do not. If possible, increase the size of the cache.
Format ^COa,b,c
Note • If you have firmware x.12 or greater this command is not required because the printer
firmware automatically expands the size of the character cache as needed.