Setting LineFeed and FormFeed Delays for Printers

Whenever an mvBase spool file containing a print job is despooled to a printer, the despooling process examines the print job for linefeed (LF) and formfeed (FF) characters. When it finds them, it inserts into the output stream, a number of ASCII NUL characters (x00) to act as delay characters. These characters were intended to allow the print head on slow dot matrix, or the paper handling mechanism on serial printers and line printers, to complete their movements for line feeds and form feeds.

With the advent of laser printers, inkjet printers and more modern printing technologies, these delay characters are generally no longer necessary and could be set to 0, especially if they cause a problem for some printers (or specialized output devices such as plotters).

These delay parameters can be set using the TERM or SET-TERM TCL commands as below:

SET-TERM [width, depth, skip, lf-delay, ff-delay, backspace, ptr-width, ptr-length, type] [(n [-m])]

TERM [width, depth, skip, lf-delay, ff-delay, backspace, ptr-width, ptr-length, type] [(R)]

lf-delay

Number of null characters output after each carriage return. These delay characters provide a pause for terminals or printers that cannot display characters as fast as the CPU outputs them. The default value is 1. The maximum value is 127.

ff-delay

Number of null characters output after a form feed character for either the terminal or the printer. The default value is 5. The maximum value is 127. If you specify 0, no form feed character is sent to either the terminal or the printer at the beginning of a page. If you specify 1, a form feed (FF) character is sent to the printer (hexadecimal '0C', CHAR(12)), but not to the terminal. If you specify 2 or greater, the form feed character is sent to both the printer and the terminal.

So to set these delay parameters to 0, it might be expected that the process running the despooler (which is started by the STARTPTR TCL command) needs to have its lf-delay and ff-delay parameters set.

In reality, the values for these parameters are taken from the process that started the despooler, i.e. the process on which the STARTPTR command was executed.

Thus if printers are started during the USER-COLD-START proc, then a TERM ,,,0,0 statement should be executed prior to the STARTPTR command(s) followed by a TERM ,,,1,5 to reset the values to their defaults.