This appendix describes how to add channel skip commands to simple ASCII files without converting the files to the Barr S/370 file format. Channel commands help your data print faster on channel printers.
Normally, S/390 channel printers do not support ASCII carriage control characters. Therefore, ASCII carriage control commands must be converted to channel commands before they can be sent to a channel printer. When it prints standard ASCII files, the Barr software automatically converts the most common ASCII carriage control characters to the corresponding channel commands.
When the software encounters an ASCII form feed (0C) character, it automatically sends a Skip to Channel 1 command to the printer. This is the only channel skip PRINT370 automatically performs for ASCII files.
When the software encounters ASCII carriage return (0D) and line feed (0A) characters, it sends the correct channel command to the printer to advance one line. Advancing one line at a time instead of jumping directly to a line slows down channel printing.
If you want to use your printer’s channel skip feature for ASCII files, and your printer stores form definitions internally, you can code the commands Skip to Channel 1 through Skip to Channel 12 with a special command sequence. When the Barr software sends the file to the channel printer, it converts the command sequence to the correct channel skip command.
The sequence consists of two bytes in the format 1F nn, where 1F signals the software to send a channel skip command to the printer and nn indicates which skip command to send. You must code the hexadecimal value of the skip that you want to perform. For example, specify 1F 02 for a Skip to Channel 2 and 1F 0C for a Skip to Channel 12.
Barr software uses machine carriage control format, so it writes the data and then sends the channel skip.
The channel skip command sequence works best for channel skips 2 through 12. The Barr software automatically converts ASCII form feed characters to Skip to Channel 1 commands, and it is more efficient to let the software convert them than to code them yourself as the ASCII sequence 1F 01.
You can add the channel skip sequences to your files by using a program editor or you can generate the sequences by changing the application programs that generate the files.
If you need to perform channel commands other than channel skips, you must use the Barr S/370 file format.