Lexmark 248X, 249X manual 137, Compressing the Character

Creating the Character Data

Each dot-column is sent to the printer as three bytes of data. To get the values of this data, convert the binary values to hexadecimal values.

First byte of data (most significant byte)	Top 8 print wires
Second byte of data	Middle 8 print wires
Third byte of data (least significant byte)	Bottom 8 print wires

The figure shows the hexadecimal value for each byte in each column of the character. For example, the first byte of column one is binary 0011 1100 or 60, x3C.

Compressing the Character

To make a compression mask, set the mask bit for each column (which is identical to the column to its left) to one. Note that only 39 columns can be compressed. The grid on page 136 shows that column 40 is the same as column 39; however, column 40 must be stored. Therefore, compression mask bit 40 is set to zero.

Next, convert the binary values to hexadecimal. The compression mask for the TM symbol is x2E74300002.

If you use compression, download only dot-columns with mask bits set to zero. Data, with mask bits set to one, is generated by the printer according to the compression mask.

Initializing the Download Area

Use the following command to initialize the download area:

<x

1B3D - download command prefix - initialize download area

0000 - byte count (low byte first) - 0

>

Section 7: Downloading Characters and Fonts 137