Tally Genicom 6600 - Manual (Page 22)

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Chapter 1 Graphics Pass
Not all GPL commands and data sent to the printer need to be in a
pass. In fact, many commands must be outside of a pass to function
properly. For instance, the command ^H sets the form length if it is
used outside of a pass, but sets the pass height if it is used within a
Pass.
At this point, it may seem difficult to decide when to use a Graphics
Pass. If there is any doubt about whether a command should go
inside or outside of a pass, refer to Appdendix F, “Command Table”
on page 287. The GPL commands fall into two general categories:
Inside A Pass
• GPL positioning commands (e.g., tabs, vertical justification, etc.)
• GPL printing commands (e.g., barcodes, lines, boxes, certain fonts, etc.)
• Block characters
Outside A Pass
Global Graphics Pass commands (i.e. commands which act on the entire
pass as a unit, such as those which cause the entire Pass to be repeated or
stored in memory for later use).
Environmental commands wuch as form length setting, Graphics Mode, and
Free Format.
Non-GPL Data
Any data you want to go to the current Control Panel emulation must be sent
outside of a Graphics Pass. Appdendix F, “Command Table” on page 287
lists all GPL commands.
Pass Spacing (Modplot)
Code V output can be affected by a Plot Mode option that is available on your
printer. Appendix G, “Modplot” on page 291 explains the Modplot option and
how it affects Code V output.
Pass Buffer Length
Data received from the host is stored in a Pass Buffer. The Printer begins to
process a Graphics Pass when it receives a Pass Terminator. The printer
processes one pass at a time, printing at the end of each pass. If the Pass
Buffer fills up before the printer encounters a Pass Terminator, it terminates
the pass and attempts to process and print it.
Buffered Form definitions and Repeat sequences cannot be processed until
the Form or Repeat Terminator is received; therefore, the entire Form
Definition or Repeat Sequence must fit into the Pass Buffer to be printed
correctly. Buffered Form execute data can be larger than the Pass Buffer. The
Printer processes this data one Pass Buffer at a time, until the Form Execute
Terminator is received.