16Chapter 1 Graphics Processing LanguageGraphics Processing LanguageThe Graphics Processing Language (GPL) consists of a set of commandsthat are used to print graphics images such as block characters, barcodes,lines, and boxes, as well as provide formatting control for the correctplacement of these images. Relatively complex images may be createdthrough the use of a few simple commands.The original version of QMS Code V (version 1) differs slightly from thecurrent version (version 2). The primary difference between the two is in theway vertical justification commands are implemented. Specifically, version 1used an approximation for 0.1 inch that has been made more precise inversion 2. If you are running an application designed for version 1, the printercan be switched to a mode that can emulate it.Graphics ModeFor the printer to recognize GPL commands, it must first be placed inGraphics Mode. When the printer is in Graphics Mode, the printer scans thedata received from the host for GPL commands, passing non-Graphics datato the current emulation. When the printer is not in Graphics Mode, Code V isdisabled and will not search the incoming data for GPL commands.Graphics Mode may be entered while the printer is in any emulation. GraphicsMode should not be entered while the printer is in Plot Mode. The printedoutput of Code V adheres to all the applicable Control Panel settings (such asLPI, CPI, Form Length, etc.).NOTE: All escape sequences in this manual are in ASCII notation.Turning Graphics Mode OnGraphics Mode is turned on with command ^PY, which must begin in the firstcolumn of a line, followed by one of the following six terminators.1. ^- (caret hyphen)2. ^* (caret asterisk)3. ^, (caret comma)4. Carriage Return5. Line Feed6. Form FeedOnce the printer is in Graphics Mode, the data it receives is read into a Passbuffer. The printer will stop looking for characters from the host and processthe data held in this buffer when one of the terminators is received. If thebuffer fills up before receiving a Pass Terminator, data in the buffer will beprocessed and printed before the printer accepts any more characters.
