User`s manual

Printers have the equivalent of an Extended Mem
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ory. For Max Secure Systems, which have no var
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nish requirements, the varnish buffer supplies the
bit map for the White Card image.
Bit-Map
Compression
Algorithm
Characteristically, a bit-map compression algo
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rithm flags data segments as either repeating or
non-repeating, specifies the bytes repeated, and the
number of repeats. For these card printers, com
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pression applies to byte-wide bit-map segments,
which the host sends with the PS, GS, Z, and vZ
commands. The PS and GS commands include pa
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rameters specifying a buffer (YMCK). Monochrome
commands Z and vZ send associated bit-map data
to the black (K) and Varnish buffers, respectively.
All of these commands include parameters that spe
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cify whether or not the command applies to com-
pressed data. For recognition by the card printer,
compressed data must conform to the following
rules:
Rule 1. When high, the most significant bit (the flag
bit) of a two-byte sequence indicates that the sec-
ond byte repeats. The remaining seven bits of the
first byte specify the number of repeats, allowing a
field-specification of from zero to 127 repeats.
Rule 2. When low, the most significant bit of a data
sequence indicates that the remaining seven bits of
the byte specify the number of the following bytes
that represent non-repeating image data. However,
only from zero to 31 repeats can occur.
Rule 3. The first byte in the data field of any com
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mand specifying a compressed bit-map must have
the compression flag high, even if a one must be en
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tered as the number of bytes repeated.
Rule 4. No other algorithm can be used to com
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press image data for this card printer.
Figure 1-2 includes examples of data strings
employing compression.
980081-001 Rev. F 1-13