Compaq 5525B/31/32 Manual De Usuario
Programmable VFC
29
Programmable VFC
Programmable VFC allows the user to specify paper movement information
other than the standard VFC definitions shown in
other than the standard VFC definitions shown in
. VFC information is
stored in the memory (RAM) table just as the standard VFC is, only the bytes
of information are loaded into RAM using the following escape sequence:
of information are loaded into RAM using the following escape sequence:
ESC&l[
byte count]W[VFC data]
The
byte count parameter specifies the number (in decimal 0 - 255) of VFC
data bytes to expect immediately following the termination of the escape
sequence.
sequence.
NOTE: An even byte count must be indicated. If an odd byte count is
indicated, the VFC table in RAM will not be overwritten and the data
bytes following the ESC sequence will be read and discarded.
bytes following the ESC sequence will be read and discarded.
VFC data is the binary data which is loaded into the VFC table in RAM. These
8-bit bytes are sent in the following order following the ESC sequence
terminator: the most significant byte of the first word followed by the least
significant byte of the first word, followed by the most significant byte of the
second word, etc. The most significant bit of each word is channel 16 and the
least significant bit of each word is channel 1.
8-bit bytes are sent in the following order following the ESC sequence
terminator: the most significant byte of the first word followed by the least
significant byte of the first word, followed by the most significant byte of the
second word, etc. The most significant bit of each word is channel 16 and the
least significant bit of each word is channel 1.
VFC Data = (MS byte) (LS byte) (MS byte) (LS byte) . . .
(word 1 = line 1) (word 2 = line 2) . . .
Once the VFC has been loaded into the RAM table, the VFC channels are
selected using the ESC&l[0 through 16]V sequence in the same manner as
the standard VFC. The standard and programmable VFC both use the same
table in RAM. Resetting the printer causes the standard VFC to be
recalculated using the current page and text (form) length and a new table to
be overwritten in RAM. The VFC table is also recalculated when the line
spacing, text length, or page length changes.
selected using the ESC&l[0 through 16]V sequence in the same manner as
the standard VFC. The standard and programmable VFC both use the same
table in RAM. Resetting the printer causes the standard VFC to be
recalculated using the current page and text (form) length and a new table to
be overwritten in RAM. The VFC table is also recalculated when the line
spacing, text length, or page length changes.
NOTE: If the I/O is configured for 7 bit data, channels 8 and 16 cannot be
downloaded with confidence since the eighth bit is used for the
communication protocol. Selecting channels 8 or 16 for 7 bit data is
not recommended.
communication protocol. Selecting channels 8 or 16 for 7 bit data is
not recommended.
Special VFC Considerations
Before loading a VFC table, it is recommended that a VFC select of channel 0
be performed. This will bring the printer to the top of the physical page.
be performed. This will bring the printer to the top of the physical page.
When a programmed VFC is loaded into RAM, the logical page length is
automatically calculated using the following formula:
automatically calculated using the following formula:
Logical Page Length (in number of lines) =
byte count /2
shows a VFC table which uses “standard” VFC
definitions and also illustrates a programmable VFC.
Example: Defining a 3.5 inch form at six lines per inch.
1 inch = 6 lines x 3.5 inches = 21 lines
1 inch = 6 lines x 3.5 inches = 21 lines