Guide to Printers and Printing

Considerations for 8-Bit Printer Attached to 7-Bit Interface

Some printers assume an 8-bit (8 bits per byte) interface to the host. Although an 8-bit printer may print when attached to a 7-bit interface, the printed output may not be acceptable. To determine if your printer assumes an 8-bit interface, consult your printer manual.

Incorrect printed output can be produced in the following situations:

• Printer command sequences may contain 8-bit values.

  If an 8-bit printer must be attached to a 7-bit interface, follow this procedure to prevent incorrect printed output.

  1. Enter the smit fast path smit lsvirprt.
  2. Select the print queue and type:

     j=!j=!
     

  3. Press the Enter key to exit.

     This prevents print file initialization strings, which may contain 8-bit command sequences, from being sent to the printer.

     Note: This also bypasses printer initialization. So, depending on the pitch, line spacing, and other attributes left by the previous print file, the output may not print correctly.

• Printer character code points may be 8-bit values where each graphical character is represented by an 8-bit integer value causing the wrong character to be printed. To avoid this problem, all the characters in the print files should be in the portable ASCII character set.
• Printed graphic files are affected when a 7-bit interface is used because some of the data points are lost.