Specifications

Appendix E— Using Direct Graphics Mode
IPL Programmer’s Reference Manual 241
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:
Data Types in RLE Files
Type Description
Byte Format, Range, and
Data Represented
Immediate
commands
• Recognized and executed as regular IPL commands or
protocol commands
• Removed from compressed data
Byte format (7-0): 000xxxx
Range: 0-31
Data represented: N/A
Compression
encodation
commands
• Used as part of the compressed graphics file to change or set
data modes, repeat lines, change the origin for the next lines
of data, or end the compress graphics file and return to IPL
command printing
Byte format (7-0): 001xxxx
Range: 32 - 63
Data represented: N/A
Low order
data
• 7 bits long and may be combined with high order data. 8
th
bit
is always set to 1.
• Can represent up to 7 bits of data (0-127)
• Must be preceded by a command byte so the printer knows
how to interpret them
Byte format (7-0): 1xxxxxx
Range: 128 - 255
Data represented: 0 - 127
High order
data
• 6 bits long and always combined with low order data. 7th bit
is always set to 1 and 8th bit is always set to 0.
• When combined with low order data, can represent up to 13
bits of data (0-8191)
• Must be preceded by a command byte so the printer knows
how to interpret them
• Printer ignores high order data followed by a command or
more high order data
Byte format (7-0): 01xxxxx
Range: 64 - 127
Data represented: 0 - 63
Bitmap data • Composed of uncompressed bytes (7 data bits per byte) that
represent columns of your graphic. 8th bit is always set to 1.
Byte format (7-0): 1xxxxxx
Range: 128 - 255
Data represented: Raw data