Asynchronous Terminals and Printer Processes Programming Manual

PRINTER PROGRAMMING CONSIDERATIONS
Using the DAVFU
than the defaults are required, the application specifies the
contents of the DAVFU by calling the CONTROLBUF procedure.
Single spacing with automatic perforation skip is the default;
the file system skips on channel 2 of the printer's DAVFU. More
specifically, for single spacing and automatic perforation skip,
set the DAVFU buffer bit for channel 2 to 1 (for lines 1-60).
The file system does not use the DAVFU for single spacing without
automatic perforation skip.
Using the DAVFU
The following discussion describes how to use the default DAVFU
settings to control form movement. Assume that line numbers
range from 1 to 254, character locations from 1 to 218, and VFU
channels from 0 to 11. The default settings are as follows:
VFU channel 0 (top of form: line 1)
VFU channel 1 (bottom of form: line 60)
VFU channel 2 (single space: lines 1-60, top of form
eject)
VFU channel 3 (next odd-numbered line)
VFU channel 4 (next third line: 1,4,7,10, etc.)
VFU channel 5 (next one-half page)
VFU channel 6 (next one-fourth page)
VFU channel 7 (next one-sixth page)
VFU channel 8 (line 1)
VFU channel 9 (line 1)
VFU channel 10 (line 1)
VFU channel 11 (bottom of paper: line 63)
Request the printer to skip to the next stop of a particular
channel by calling CONTROL 1, parameter = channel number. The
channel number must be in the range 0-11.
! skip to channel 0 (top of form)
CALL CONTROL ( FILENUM, 1, 0 );
! skip to channel 5 (next one-half page)
CALL CONTROL ( FILENUM, 1, 5 );
Initializing the DAVFU
The I/O process reinitializes the DAVFU with the default values
if the application process issues a CONTROL 1, parameter = 0
(skip to top of form) immediately after the file is opened or
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