Xerox 721P87491 manual Control-D as binary data and end-of-job, Control-Z and superfluous errors

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POSTSCRIPT

Control-D as binary data and end-of-job

The fact that control-D can be a valid PostScript end-of-file (EOF) delimiter in one communications protocol and invalid in another creates a paradox for PostScript printers that must accept jobs created for either communications mode without any indication of which communications mode was used. The recommended solution is described in “Solution to control-Z and control-D problems.“

How PostScript jobs are delimited—separated from each other in a continuous stream of jobs—is not simple. Remember that the actual PostScript interpreter has no concept of a job. There is no PostScript job end operator. The job server, which is external to the interpreter, must make the job begin and job end determination and act accordingly. It does this by considering a PostScript job to be a simple byte stream input file. When end-of-file (EOF) is reached, the job server restores the PostScript state for the next input file (job).

The way input files—or jobs—are sent to a PostScript printer depends on the communications protocol used to transfer the PostScript document to a PostScript printer. For example, when a LaserWriter is connected to an Apple Macintosh over the AppleTalk serial communications channel, AppleTalk protocol encapsulates PostScript jobs as files. The LaserWriter AppleTalk software delimits PostScript jobs based on the AppleTalk file protocol. AppleTalk encapsulates files in its own high-level protocol. This allows AppleTalk to support transparent data transmission; that is, there are no byte codes reserved for AppleTalk communication functions. This means that all byte values are valid in a PostScript master.

This is not true when you are connecting an IBM PC to a LaserWriter over the LaserWriter asynchronous serial communications (RS232 or RS422). There is no high-level protocol, such as AppleTalk has, that delimits files, so the control-D character code (octal 004) was chosen to delimit input files. The LaserWriter asynchronous software handler strips out the control-Ds and sends an EOF to the PostScript job server. This prevents sending binary PostScript jobs (jobs where all byte codes are valid PostScript data) through the asynchronous serial communications port. In contrast, the LaserWriter can accept binary PostScript jobs over AppleTalk since it is data transparent.

Control-Z and superfluous errors

Control-Z is not used by the LaserWriter RS232 asynchronous serial communications software; yet it often appears at the end of many PostScript masters and can pose problems.

Control-Zs appear at the end of many PostScript files created under the Microsoft Disk Operating System (MS-DOS). They cause errors on a LaserWriter, but this is usually unnoticed because the control-Z undefined command error occurs after the last page is printed. In addition, because the default error handling mode of the LaserWriter is to send the error back to the creator through the communications port, most users never see the error. This is not the case for PostScript products that have been configured to print a break page on every error.

Because the majority of the error messages caused by control-Z are superfluous, it is recommended that control-Zs used as end-of-files be ignored.

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XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES

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Contents Version 7.1 August 2000 721P87491 Page Operation safety Laser safetyOzone information Conductor may result in risk of electrical shock. grounding Table of contents PostScript Vipp IndexViii About this guide ContentsConventions Introduction Related information Related publicationsPostScript publications HP PCL 5 publications Vipp publicationPCL Maintaining image qualityOFF PCL 5 media support PCL 5 font supportPCL 5 fonts installed with NPS software PJL commands PCL command supportPCL Copy command PCL Copy command example Duplex PCL Copy command examplePCL Duplex commands PCL Duplex commands DocuPrint NPS Collated HP LaserJet 4siPCL Job Separation command PCL Paper Source command tray assignment PCL media selectionPrecedence in selecting media PCL Output Bin command PCL Offset Registration commandsPCL 5c support PCL 5 coding recommendationsPCL 5c coding recommendations PCL 5c functions not applicable to DocuPrint NPSDriver recommendations for PCL 5c Limitations for custom PCL 5c driversImplementation-dependent operations Coordinate system default matrixFloating-point arithmetic and math operators Adobe Type1 PostScript fonts FontsFont Typeface Loading fonts User-defined fontsUsing Adobe Type 1 fonts Type 1 fontsUsing a Type 1 font in a document Producing Type 1 fonts for use with DocuPrintPostScript language extensions PostScript with embedded PJL commandsSystem Dict User Dict Server DictIdleTime Dictionary Status DictDfltkIdleArry needflush Nonstandard definitions Printer resolution and resolution enhancement Appearance consistencyExamples of nonstandard definitions Statusdict UserdictDpi image Printed on a 300 dpi printer Printer imaging characteristics Font consistency Proprietary PostScript extensionsControl-Z and superfluous errors Control-D as binary data and end-of-jobSolution to control-Z and control-D problems Multiple jobs in one input file DocuPrint NPS implementation of PostScript Level Simulated mixed plexScan conversion details Printer Controller operationsStroke Fill ShapesCurved shapes Zero-width lines strokesImages Image quality Rendering of color and gray values transfer function PostScript printer description PPD files Implementation limitsImplementation limits File operators and standard devicesQuantity Limit Description Path limits PostScript VM limitsSetCacheDevice Device orientation and setscreen operatorObsolete operators-banddevice, framedevice, renderbands PostScript storage object size limitsArc to Bezier conversion-pathforall Print performance related to image printing Creating the necessary PostScript Ccitt Group 3Scan order and rotation Purpose Image orientation mismatch aImage orientation mismatch B 10.Image pixel sequence example Considerations SummaryScan resolution and scaling 11.Scaling and resolution example12.PostScript with embedded image normal scan order MaxX exch def /minY exch def /minX exch def 14.Actual PostScript print Page Vipp Functionality Operating environmentVipp line mode extension XGFNub Page Symbols CcittIndex PCL PPD Index

721P87491 specifications

The Xerox 721P87491 is a remarkable printing device that showcases advanced technology tailored for professional environments, ensuring high-quality output and efficiency. Aimed at meeting the demands of busy offices, this model is recognized for its reliability and innovative features.

At the core of the Xerox 721P87491's appeal is its robust printing capabilities. It offers an impressive resolution, enabling the production of crisp and clear documents, whether in black and white or color. This high-resolution output is particularly essential for businesses that require detailed graphics, intricate charts, or professional-grade presentations.

One of the standout features of the Xerox 721P87491 is its impressive speed. It is designed to handle high-volume printing, significantly enhancing productivity in fast-paced work environments. With a rapid print speed per minute, users can expect swift processing of print jobs, ensuring that document delivery times are minimized.

The device also boasts advanced connectivity options. It supports both wired and wireless connections, allowing for seamless integration into a variety of office networks. This flexibility facilitates printing from multiple devices, including desktop computers, laptops, and mobile devices, enhancing overall workflow and collaboration within teams.

Additionally, the Xerox 721P87491 incorporates user-friendly interface options. With an intuitive touchscreen display, navigating the printer's functions becomes simpler. Users can easily access common features, adjust settings, and manage print jobs efficiently.

Another notable characteristic is its advanced security features. Given today's emphasis on data protection, the Xerox 721P87491 is equipped with robust security protocols to safeguard sensitive documents. It includes features like secure print, which holds documents until the authorized user enters a PIN, ensuring confidentiality in high-stakes environments.

Moreover, the Xerox 721P87491 demonstrates an emphasis on environmental sustainability. It is designed to be energy efficient, reducing power consumption during both idle and active states. The printer also supports duplex printing, which helps decrease paper use, contributing to a more sustainable office practice.

In summary, the Xerox 721P87491 is a versatile printing solution that merges efficiency, quality, and advanced technology. With high-speed printing, intuitive controls, robust security features, and a commitment to sustainability, it stands out as an excellent choice for businesses aiming to boost productivity while maintaining high standards. Its capabilities make it a worthy investment for any modern office environment.
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