Intermec EasyCoder 3440 User Manual page 14

In cases where patterns do not exist, you can send uncompressed bitmap data
to the printer. You can mix raw bitmap data and RLE commands to ensure the
most efficient way to download a graphic.
The RLE file may contain five types of data, each of which is one byte long:
regular IPL commands or protocol commands. Immediate commands are
removed from the compressed data.
used as a part of the compressed graphics file to change or set data modes,
repeat lines, change the origin where the next line or lines of data will print,
and to end the compressed graphics file and return to IPL command parsing.
Low order data is 7 bits in length and may be combined with
high order data. A single low order data byte can represent up to 7 bits of data
(0-127). Combined with a high order byte, the combined data can represent at
most 13 bits of data (0 - 8191). Data bytes cannot exist by themselves, but must
be preceded by a command byte so that the printer knows how to interpret
them. Any data may be represented by either combined data or just low order
data. The 8th bit is always set to 1.
High order data is six bits in length and is always combined
with low order data. The combined data can represent at most 13 bits of data
(0 - 8191). Data bytes cannot exist by themselves, but must be preceded by a
command byte so that the printer knows how to interpret them. Any data may
be represented by either combined data or just low order data. The printer will
ignore high order data followed by a command or more high order data. You
must set the 7th bit to 1 and the 8th bit to 0.
Bitmap data is composed of uncompressed bytes that represent
columns of your graphic. The uncompressed bytes contain 7 data bits per byte.
The 8th bit is always set to 1.
Use this table to understand how the printer uses these five types of data:
Immediate commands
Compression encodation commands
Low order data
High order data
Bitmap data
Immediate commands are recognized and executed as
Compression encodation commands are
0 0 0 x x x x x
0 0 1 x x x x x
1 x x x x x x x
0 1 x x x x x x
1 x x x x x x x
0 - 31 N/A
32 - 63 N/A
128 - 255 0 - 127
64 - 127 0 - 63
128 - 255 Raw data