HP Printer Job Language (Printer Languages)

HP Printer Job Language (PJL)
Printer Job Language (PJL) was developed by Hewlett-Packard to provide a method for switching printer languages at the job level, and for status readback between the printer and the host computer. PJL adds job level controls, such as printer language switching, job separation, environment, status readback, device attendance and file system commands. Unlike PCL and HP GL, which control the placement of dots on the printed page, the Printer Job Language (PJL) commands provide job level control. PJL was primarily designed for use by application developers and technical support personnel. One of the main features PJL offers is the ability to switch printer languages between jobs. Applications supporting PJL can print one job using PCL and then print the next job using PostScript or another printer language – without any operator intervention. PJL can also command two–way communication with the printer.HP’s Printer Job Language (PJL) provides control above PCL and other printer languages. The four major functions provided by PJL are:
Printer language switching
Job separation
Printer configuration
Status readback from the printer
PJL commands may be used to change printer default settings.
PJL can also be used to change the printer’s control panel settings, that is changing default settings without using the control panel, and modify the message displayed on the control panel.
The PJL command structure
PJL was conceived as an extension to PCL, it is now supported by most PostScript printers. Many printer vendors have extended PJL to include commands proprietary to their products. Not all PJL commands documented by HP are implemented in all HP or other vendor products. PJL resides above all the other printer languages and parses commands first. The syntax mainly uses plain English words.
The following example shows the structure of PJL commands. In this example, first a PCL job prints, then PJL switches the printer language to PostScript to prepare for the following PostScript job.
%-12345X@PJL
@PJL ENTER LANGUAGE = PCL
– PCL job data –
@PJL ENTER LANGUAGE = POSTSCRIPT
– PostScript job data –
%-12345X
• The Universal Exit Language (UEL) command %-12345X
exits the current printer language and returns the control to PJL.
• The UEL command must be immediately followed by the PJL
command prefix @PJL.
• To terminate all PJL commands a line termination (line feed)
is required. A preceding carriage return is optional.
• After the UEL command the PJL command sets the printer
language to PCL.
• The PJL command is followed by the data of the PCL print job.
• Another UEL command is used to finish the PJL job.

HP Graphics Language (HP GL), (Printer Languages)

HPGL, sometimes hyphenated as HP-GL, is the primary printer control language used by Hewlett-Packard plotters. The name is an initialism for Hewlett-Packard Graphics Language. It later became a standard for almost all plotters. Hewlett-Packard's printers also usually support HPGL in addition to PCL.
The Hewlett Packard Graphics Language (HP GL) is widely used by pen plotters used to produce engineering drawings. HP GL has been widely emulated by other plotter manufacturers, and is the de facto standard language for pen plotters. A pen plotter is a slow device, a complex drawing can easily take have an hour to plot, and plotters are often noisy and difficult to set up. For these reasons many laser printers offer an HP GL emulation, normally copying the HP7475A desktop plotter, which can be used for draft prints of drawings.
As most laser printers do not print in color, and cannot print on the very large paper sizes used by plotters, they are normally only used for draft prints, but in a few situations, such as printed circuit board designs, laser printers are used in preference to plotters. HP GL version 2 has been incorporated into the PCL 5 language to provide PCL with vector graphics capabilities. HPGL uses two-letter mnemonics as instructions for drawing lines, circles, text, and simple symbols. HPGL has evolved over the years as HP added features to its line of pen, electrostatic, inkjet, and laser plotters and printers.
HP-GL/2
There is one primary drawback to HPGL: it is bulkier than other plotting languages, which means it takes longer to transmit an HPGL plot file. To overcome the limitation, Hewlett-Packard in 1988 introduced HPGL/2, which featured "polyline encoding," a form of data compression that reduces the plot file size and, hence, transmission time by two-thirds.
The original HP/GL-Language does not support definition of line width, as this parameter was determined by the pens loaded into the plotter. With the advent of the first inkjet plotters, line width for the "pens" specified within the HP/GL-files had to be set at the printer so it would know what line width to print for each pen, a cumbersome and error-prone process. With HP/GL-2, definition of line width was introduced into the language and allowed for elimination of this step. Also, among other improvements a binary format was defined that allowed for smaller files and shorter file transfer times, and the minimal resolution was reduced.

PCL5 & PCL6 (Printer Languages)

PCL 5

Released with the following printers: HP LaserJet III, HP LaserJet IIID, HP LaserJet IIIP, and HP LaserJet IIISI series printers. Provided ultimate office publishing functionality. New publishing capabilities included font scaling, outline fonts and HP-GL/2 (vector) graphics. PCL 5 was designed for more complex desktop publishing, graphic design, and presentation applications. Introduced in 1990 with the HP LaserJet III series printer.

The LaserJet II was superseded by the LaserJet III, which incorporated the PCL 5 language. The LaserJet III was an 8 p.p.m. office printer, other HP PCL 5 printers included the IIID (8 p.p.m. duplex), the IIIP (4 p.p.m) and the IIISi (17 p.p.m. duplex). PCL 5 represents a major advance over previous versions, and while it is still an Escape Code Language, it offers most of the capabilities of a Page Description Language. The primary features added for PCL 5 were Outline Fonts and Vector Graphics. The importance of these features cannot be underestimated, as using a combination of these two features it is possible to define almost any imaginable feature of a page. The vector graphics commands were provided by adding a version of HPGL (Hewlett-Packard Graphics Language), the language used by Hewlett-Packard Pen Plotters, to the PCL command set.

PCL 5 is largely backwards compatible with PCL 4, but the change from bitmap to outline fonts created some small incompatibilities. PCL 5 is eminently suited to complex documents, and works well with desktop publishing, graphics design and presentation applications.

In addition to PCL 5, the LaserJet III series introduced the technique called "Resolution Enhancement", in which small dots are automatically placed at the edges of lines and characters to reduce the ragged edge sometimes visible on 300 d.p.i. prints.

PCL 5e (Enhanced)

Released with the following printers: HP LaserJet 4, HP LaserJet 4M, HP LaserJet 4L, HP LaserJet 4ML, HP LaserJet 4P, HP LaserJet 4MP, HP LaserJet 4Plus, HP LaserJet 4Mplus, HP LaserJet 5P, HP LaserJet 5MP, HP LaserJet 5L, HP LaserJet 5L-FS, HP LaserJet 5Lxtra, HP LaserJet 6L, HP LaserJet 6LXI, HP LaserJet 6LSE, HP LaserJet 6P, HP LaserJet 6MP, HP LaserJet 6PXI, HP LaserJet 6PSE, HP LaserJet 5si, HP LaserJet 8000, and HP LaserJet 9000 series printers.

Provided bidirectional communication between the printer and the PC. Features a wider selection of fonts for use primarily with Microsoft Windows applications.

The LaserJet III series was replaced by the LaserJet 4, which introduced a higher printing resolution of 600 d.p.i., a fast bi-directional Centronics-type parallel port (Bi-Tronics) so that the printer can give more status information to the computer, and a selection of fonts dedicated to use with Microsoft Windows application software. There are a few minor enhancements to PCL 5, resulting in PCL 5e (enhanced), primarily allowing the printer to talk to the computer to report status messages, errors etc.. The enhancements in PCL 5e do not have any significant effect on the page description functionality in the language. The LaserJet 4 series of printers includes the LaserJet 4 (600 d.p.i., 8 p.p.m.), the LaserJet 4L (300 d.p.i., 4 p.p.m.), the LaserJet 4P (600 d.p.i., 4 p.p.m.) and the LaserJet 4Si (600 d.p.i., 16 p.p.m.). In addition to the basic range, all the LaserJet 4 range is available with the Adobe Postscript level 2 Page Description Language (see below) built-in in addition to PCL 5e, these models are designated by the letter "M" after the number (4M, 4ML, 4MP, 4SiMX).

PCL 5C (Color)

- Released with the following printers: HP Color LaserJet, HP Color LaserJet 5, HP Color LaserJet 5M, HP Color LaserJet 2500, HP Color LaserJet 4500, HP Color LaserJet 4550, HP Color LaserJet 4600, HP Color LaserJet 5500, HP Color LaserJet 8500 and HP Color LaserJet 8550 series printers.

Provided the commands needed to support color printing.

There is a version of PCL 5, PCL 5c, which issued on HP color ink-jet printers and the HP ColorJet color desktop laser printer. PCL 5c is compatible with PCL 5 but adds the commands needed to support color printing.

PCL 6 -

Released with the following printers: HP LaserJet 4000 series, HP LaserJet 4100 series, HP LaserJet 2100 series, HP LaserJet 2200 series, HP LaserJet 1200, HP LaserJet 3200, HP LaserJet 3300, HP LaserJet 4200 series, HP LaserJet 4300 series, HP LaserJet 5000 series, HP LaserJet 5100 series, HP LaserJet 8000 series, HP LaserJet 9000 series printers.

Features new modular architecture that can be easily modified for future HP printers; faster return to application; faster printing of complex graphics; more efficient data streams for reduced network traffic; better WYSIWYG printing; improved print quality; truer document fidelity; and complete backward compatibility.

PCL 6 commands were designed by HP to closely match Microsoft Windows graphical direct interface (GDI) commands. As a result, users get improved performance and better print quality. For example, users will regain control of their PC and application sooner because PCL 6 allows the printer driver to translate GDI to PCL 6 faster than before. Network throughput will improve because PCL 6 uses smaller, more compact commands than previous versions used. Complex graphics will print faster because PCL 6 is specifically designed for graphics while gray-scale images, which are processed as objects, appear smooth and even, offering superior print quality for graphics and scanned images. Design consistencies between PCL 6 and GDI also yield better WYSIWYG printing.

Although PCL6 generates smaller file sizes in certain network configurations, the speed of today's host processors and networks may offset the performance benefits of having smaller file sizes.

Hewlett Packard Printer Command Language (Printer Languages)

Hp PCL or Hewlett Packard Printer Command Language was introduced by the Hewlett-Packard. It is independent of host system, device drivers, I/O interface, and network communications. Its purpose is to bring all HP printers together under a common control structure. HP used it in its first desktop laser printer. PCL is an Escape Code language. HP has been using this language for its dot-matrix and inkjet printers before the invention of laser printers. PCL commands are compact escape sequence codes that are embedded in the print job before being sent to the printer. PCL fonts quickly translate application output into high quality raster print images. PCL has several versions available.

PCL 1

PCL 1 was introduced in 1980. It is simple language having capabilities for basic printing. PCL 1 prints nothing but only text. Supported by all HP LaserJet series printers (except the HP LaserJet 3100 and 3150 series products).

PCL 2

PCL 2 added Electronic Data Processing/Transaction functionality. Supported by all HP LaserJet series printers (except the HP LaserJet 3100 and 3150 series products).

PCL 3

PCL 3 was introduced in 1984 with the original HP LaserJet. Released with the following printers:

HP LaserJet series printer,

HP LaserJet Plus series printer.

It provided the commands and features required for simple high quality word processing and data printing. Allowed for the use of a limited number of bitmapped fonts and graphics.

PCL 3 provided simple word processing and data sharing. It supported not only small bitmap fonts but also small bitmap graphic printing. Many other manufacturers emulate PCL 3 referred to as LaserJet Plus emulation. PCL 3 is still in use on several impact printers which replaced the obsoleted HP models. It does not support downloadable or scalable fonts. It is pixel based printer language that primarily describes images by pixel.

PCL 4

Released with the following printers: HP LaserJet Series II, HP LaserJet IID, HP LaserJet IIP, and HP LaserJet IIP Plus series printers.

Provided new page printing capabilities. Supported macros, larger bitmapped fonts and graphics. Introduced in 1985.

The LaserJet Plus printer was superseded by the LaserJet series II, also an 8 p.p.m. printer. The LaserJet II series of printers included the LaserJet IIP, a 4 p.p.m. personal printer, and the LaserJet IID, a duplex version of the LaserJet II. The LaserJet II introduced the PCL 4 language, which built upon PCL 3 by adding the ability to use more, larger bitmap fonts, and more bitmap graphics. The standard LaserJet II could manage just over half a page of bitmap graphics, but with the addition of some extra memory this could be expanded to a whole page.

PCL 4 was introduced on the HP LaserJet II in 1985, adding macros, larger bitmapped fonts and graphics. PCL 4 is still popular for many applications.

PCL 4 was backwards compatible with PCL 3 (PCL 3 jobs would print perfectly well under PCL 4), but the additional features took it well beyond the bounds of word-processing, and allowed it to be used for charts, graphics and simple desktop publishing. PCL 4 has been superseded for office printers, but is still commonly used in personal printers as it requires relatively little processing power in comparison with later versions of the PCL language. The version of PCL 4 used on the LaserJet IIP was a slightly enhanced over the version used on the standard LaserJet, and provided a compression method for bitmap graphics to reduce the amount of data which the computer had to send to the printer.

Laser Printer Problems

Are you having printing issues with your printer? Specifically, is the print quality not as good as it used to be? Here's how to solve problems that may plague your laser printer. There are a variety of print quality defects which occur from time to time in laser printers, most of these are:

Vertical White Lines
If you find you have white stripes throughout the printout, then the transfer corona wire is most likely the problem. There may be a problem getting the charge to the paper, resulting in toner missing on the page in areas. Otherwise there is blockage in the developer unit preventing a small area on the developer roller from receiving toner. Clean the path between the developing roller and the “doctor blade” with the corner of a sheet of paper if developing unit is user removable part, but this is not possible on printers using print cartridges.

Spotty Print
If spots appear at regular intervals on the printout, the printer’s drum may be damaged or toner may be stuck to the fuser rollers. Try wiping off the fuser rollers. Check the drum for damage. If the drum is damaged, you must get a new toner cartridge.

Black Pages

In some printers a black page can be occur when the charger corotron is broken or not properly connected. Examine the charger corotron to see it is broken. Usually it comes with print cartridge or photoreceptor unit, replace the print cartridge or photoreceptor unit with a new one. If the charger corotron is not broken, or can not be seen to check, try removing and reinstalling the print cartridge or photoreceptor unit, as the electrical contacts between the removable unit and the main part of the printer may not be connecting properly.

Creased Pages

Sometimes paper creases in the printer. The most common cause of creases is damp paper, sometimes a crease is simply a paper jam. Laser printers have up to four rollers. In addition to the heat and pressure rollers of the fusing assembly, rollers are designed to move the paper from the source tray to the output tray. These rollers crease the paper to avoid curling,which would cause paper jams in the printer. If the creases are noticeable, replace the paper, and if the problem persists check all the potential causes of misfeeds, paper jams and skewed prints. No hardware solution exists for this problem. This is simply a side effect of the process.

Blank Paper

Most common cause of a blank printout is empty toner cartridge. Print a test page from the printer or OS to confirm the problem. If nothing prints out, pull the toner cartridge, if it is empty replace it with a new one. In some printers a white page can occur when the transfer corotron is broken or not properly connected. Examine the transfer corotron to see that it is not broken. If the transfer corotron is broken a service engineer will probably be required to fix it, as the transfer corotron is usually built into the main body of the printer. If the transfer corotron is not broken try removing and reinstalling the printer consumables such as the toner cartridge and photoreceptor cartridge or the print cartridge.

Incomplete Characters

Incompletely printed characters on laser-printed transparencies can sometimes be corrected by adjusting the print density. Remember to use only materials approved for use in laser printers. characters are occasionally missing from the text there is probably a communications error. Check printing cable connections, otherwise replace it with a new one.

Ghosting
Ghost images appear on the printed page because of bad cleaning blade or improper charging of the drum unit. Ghost images appear on the next printed page if cleaning blade does not clean the drum surface. Drum/ photoconductor is very sensitive to light, so special care should taken while pulling it out.

Fuzzy Print
Low quality or dump paper may effects sharpness of the printed image or the characters. The problem is not the printer, but the paper. Always store paper in a dry place to avoid this problem. Avoid paper that is too rough too smooth. Paper that’s too rough interferes with fusing of characters and their initial definition. If the paper is too smooth (like some coated papers, for example), it might feed improperly, causing distorted or overwritten characters.

Light Ghosting and Dark Ghosting
A variety of problems can cause both light and dark ghosting, but the most common source of light ghosting is developer starvation. If you ask a laser printer to print an extremely dark or complex image, it can use up somuch toner that the toner cartridge won’t be able to charge enough toner to print the next image. The proper solution is to use less toner by doing the following:

a) Use low resolution
b) Chang the pattern
c) Print a completely blank page prior to the page with the ghosting image.
Misfeeds
A misfeed occurs if the printer fails to feed a sheet of paper from the paper feeder. Misfeeds are normally caused by paper which is unsuitable for the printer, either because it is too light, too heavy, or too smooth, however misfeeds do occur with the correct paper. Old or dirty feeding rollers may cause misfeeds. Clean the feeding roller rubber with water and cloth.

More Tips

Most printers can run a self-test if you hold down one or more buttons on the control panel while the unit powers up. If you use a shared printer, take out a test print-out page first to ensure that the printer itself is functioning properly. Also make it sure that the computer is connected to the same AirPort network if your printer is connected to an AirPort Base Station. If the test page looks good, then the problem lies with your data cable, PC, or software. Usually you can print a test page by:

• By holding down the “Online” key for 5 seconds
• By pressing the “Up” and “the “Down” arrow key and than immediately pressing the “Enter” key
• If your printer has “Menu” key, press it and search for “Test page” under this selection.
• Go to the Windows Control Panel, Printer and Faxes, right click the printer, select properties and click “Print Test Page”.

Also be sure that:

• Your printer is the selected printer in the Print dialog.
• Select it from the Printer pop-up menu if you do not find it listed.
• Take care that your operating software is up-to-date.
• Also ensure that you are using the manufacturer's latest printer driver.
• Try deleting and then re-adding your printer through the Printer Setup Utility.

Manufacturer Specific Printer Language

I have described some details of HP PCL and Adobe Postscript. There are other languages which individual printer manufactur use. In some cases the manufacturers provide their own language to use with the printer. Manufacturer also wish to have their language adopted as the industry standard, but in the real world every language has its advantages and disadvantages. Each language has its own role in industry to meet different printing requirments. Sometimes none of these languages fulfils the user requirments so professional programmers are employed to create custom applications supporting unique features.
Kyocera PreScribe
Kyocera has its own manufacturer specific language. Kyocera uses Kyocera Prescribe in addition to HP PCL emulation. Prescribe is a good language for true type fonts. Mostly it is being used for minicomputer applications and applications using barcodes.
IBM IPDS
IBM IPDS (Intelligent Printer Data Stream) has more features for IBM mainframe. IBM introduced "Advanced FunctionPrinting" (AFP). AFP is a way in which complex documents can bedescribed on IBM mainframes and minicomputers, and is converted intothe IPDS print language by the operating system on the computer. IPDS does not support other manufacturer's drivers. User must have an IPDS comatible print to print a document. But some printer manufacturers provide IPDS emulation to make PCL or Postscript available to IBM systems. User has to use an external computer to use these emulations which translates IPDS commands into PCL or Postscript.

About Printer Drivers

In computers, a printer driver or a print processor is a piece of software that converts the data to be printed to the form specific to a printer. The purpose of printer drivers is to allow applications to do printing without being aware of the technical details of each printer model.
Printer driver resides on the computer and gives the computer or the OS to understand the printer capabilities. Operating system use drivers to use all the printer features.
Windows is supplied with the popular printer drivers. To check windows built in drivers, go to Control Panel, Printers and Faxes, Add printer. But be careful about new printer models and less common printer model drivers. These drivers can be downloaded from manufacturer's website or you can install them from the CD provided by the manufacturer. Printers have some built in fonts and other font they have to download. Printer driver tells the computer what printer language printer uses and which font are built in. It also manages all the optional components of the printer like duplex unit, optional bypass, optional paper feeders unit and so on. I remember one of our customer complained that his printer's paper tray is not feeding papers. He was trying to configure HP's small printer driver with a heavy duty printer of another manufacturer. I just installed the correct driver and everything was OK.
Manufactures of the less popular printers usually produce printer drivers for the most common operating systems, but they are often unwilling to produce drivers for the specialist and less popular systems or for old systems. Because of this, printer driver provide a long term support problem, the majority of operating systems are updated and upgraded frequently, and the printer driver designed for an old version of the system may not be suitable for the latest version. If you want to buy a printer, it is better to have a popular printer which the OS provides driver for. Otherwise you may face printer driver problem soon or later. It is good habbit to check the manufactur website for drivers before buying a new one.

Printer Emulation

Emulator means someone who copies the words or behavior of another Synonyms. In computer sciences hardware, software or a combination of the two that enables a computer to act like another computer and run applications written for that computer is called emulator. In the past, it was often a hardware add-on that actually contained an instruction execution module for the emulated computer. Today, "emulator" more often refers to software, which provides a translation layer from the emulated computer to the computer it is running in. understand printer emulation, remember that a printer receives commands from the computer. These commands are in a specific printing language. Many manufacturers have developed printing languages but some of them have become industry standards. To meet the industry requirement manufacturers try to make their printers compatible with these de facto standards. PCL and Postscript are most popular languages and have become a standard, other manufacturers equip their printer according to the specifications of these languages. For example, while PCL was developed by Hewlett–Packard, it was widely copied by other manufacturers who offer emulations of HP printer. By the emulation of a HP printer another printer is able to understand PCL. If you are using an emulated printer, you may find “Laser Jet IIp compatible” or “PCL5 compatible” etc on it.

The term emulation especially applies to PostScript printers because Adobe itself does not produce printers and each PostScript printer produced by any manufacturer emulates PostScript. The term emulation also applies to printers that do not emulate the printer or the printing language of another manufacturer but that emulate another type of devices. For example some Laser printers have the ability to emulate other graphic output devices such as pen plotters. These printer emulate HP GL language which is used by pen plotters. In some graphic applications a plotter can take 30 minutes to print a complex drawing, while the draft output is produced from a laser printer in a few seconds. It is possible for designers to print a sample on laser printers and after finalizing the drawing it can be printed on plotter.
Adobe does not sell printers but it sells Postscript license to the manufacturers. Before Postscript Level 2, the license fees charged by Adobe were high, so some manufacturers tried to emulate the PostScript language. But nowadays license fees has been reduced and manufacturers prefer to use Postscript instead of emulated languages.

Printer Languages Types

Printer languages can be categorized into two types:

1. Page Description Language
2. Escape code language
Page Description Language
As its name describes, page description language (PDL) is a language that describes the appearance of a printed page in a higher level than an actual output bitmap. PDL's are high-level languages that specify the format of a page generated by a printer; they are translated into specific codes by any printer that supports the language. It is generally more versatile and allow more complex pages and graphics to be created. An overlapping term is printer control language. Usually PDL's are used for advance documents such as presentation materials, advertising brochures etc. Page description languages are normally used by software packages which produce sophisticated, highly formatted output, including graphics design programs, advanced word processing packages, spreadsheets with extensive charting capabilities, and desktop publishing packages.
Most commonly used PDL's are:
PDF, Portable Document Format by Adobe
PCL, Printer Command Language by Hewlett-Packard
PostScript Language one of the most noted page description languages, is a fully fledged programming language
Some PDL's are or have been made open standards. There are also other proprietary languages whose details are not publicly disclosed.
Escape code languages
Escape code languages are generally characterized by the structure of the commands they use, each command is prefixed by a special code (normally the escape code, hence the name) to signify that the following characters are a command, and not data to be printed.Printing from a windows application is very easy. Just open the File menu and select “Print” command. Windows operating system can be configured in different way with printer. Currently Novell Netware, PPR. IPP and Email printing are supported by Windows.
Escape code languages are suitable for simple documents and not good for complex pages like graphic design etc. They are less flexible than PDL. Simple documents such as letters, database printouts and document containing simple graphics can be printed with an acceptable printing quality. Most escape code languages do not offer sophisticated typographic features, they can use a range of different fonts but can print text in a limited number of sizes. They also can not handle special effects such as 3 D printing, printing text at an angel etc.
Disadvantages of Page Description Languages
a) Post description languages require a lot of processing power, so PDL printers format data more slowly than ECL printers.
b) PDL printers need more powerfull printer controller, with the result that most PDL printers are more expensive than escape code printers.
c) Some old applications can not use PDL printers. There must be an escape code language built into PDL printers to overcome this problem.

The task of a printer language

In my previous post I gave a brief introduction of printer languages and printer fonts. Now we'll see printer languages in a little detail. Suppose you went to a new country and do not know the local language. How you will communicate if you are in a trouble? You need a interpreter ofcourse. In the same way, when you type something in any application, printer does not recognize it. Say printer is blind for every thing you typed in Microsoft Office or any other text editor. We must set some rules to communicate between the applications and printer. These rules or commands are called printer language. It is the set of commands printer obeys to format data sent from a computer. Whenever you sent "Print" command the computer embedded these commands in the printing data. This is done by a special software running on the computer --the printer driver. Printer driver formates the data and sends it to the printer, printer receives and interprets the data. Most popular printer languages are:

HP PCL (Hewlett-Packard's Printer Command Language)

Adobe Post Script

Printer languages are designed diffterently for diffterent types of printers. Some are written for Laser printers, some are designed for older, simpler printer but can be interpreted by som laser printers. Be careful while choosing a printing language. Most computer applications only support a subset of the printer language in use. If you are workin in Macintosh environment, than you should prefer PostScript because most applications in macintosh output PostScript which is an industry standard language for describing complex pages. In Mainframe and Minicomputer usually support printer languages proprietary to their manufacturers.

Perhapes most of you work on their personal computers only, Here is a goog news fot them. Most IBM-compatible personal comuters support all commonly used languages as well as handfull of older languages designed for dot- matrix or daisywheel printers.

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Printer Languages, A Brief Introduction

Lets see how a printer exactly prints the characters on the paper? Printer actually use some special language to print characters or images. I shall explain the detail in next few post. But here we'll have a brief introduction:
There are two major aspects of printing:
1. Printer Language
2. Fonts
If you are using windows operating system, you can see the installed font in Control Panel, Fonts. These fonts display characters on your computer display. In the same way printer needs a set of fonts to print correctly.
The communication between a computer and a printer ranges from managing print jobs to describing the contents of single pages. Because of this wide range of tasks, different printer languages have been developed, which are more or less specialized in performing specific tasks.
Another point should be remembered that manufactures have developed languages to controll thier own printer models and to perform specific task. PCL and Postscript are most widely used languages because of there capabilities and have become defacto standard.
Computer users are from different parts of the world. They prefer to type and print in their own language. So their are different languages and different character systems. For example, besides the Latin alphabet there is a Cyrillic alphabet as well as Arabic, Japanese, and Chinese characters and symbols. Even the Latin alphabet of some modern languages has been extended in different ways by symbols like ä (German) and å (Danish).
There are two aspects concerning fonts:
1. Fonts should cover symbols and characters from all over the world
2. They should support different styles and sizes and different technologies that are used to visualize characters (bitmap and scalable fonts).
All this means, that the fonts made for the use by a computer are part of a system that is determined by human and cultural aspects as well as technical aspects.

Windows Printing (Printer Basics)

Printing from a windows application is very easy. Just open the File menu and select “Print” command. Windows has been offering different methods to configure printer with the OS. Currently widows support Novell Netware printing, LPR printing, IPP printing and Email printing.
Which Print Method to Use?
The optimum Windows printing configuration depends upon your particular environment including user and administrator experience and preferences. Netware print Services will be utilized when an Netware Server is present. LPR printing is being used most commonly if TCP/IP is already in use. NetBEUI Peer to Peer printing is most often utilized when a centralized NetWare or Windows Print Server is not used. IPP or e-mail printing
is utilized when printing across the Internet is required.
In general, remember the following about different printing methods:
LPR:
Printing to a Windows LPR spooler over TCP/IP. I have described what is “spooling” in my last posts. Just remember that this function may be helpful if you are going to print a lot of data and also want to work on the application from which you are printing. By using “spool” all printing data is temporarily saved in another folder and transferred to the printer form there, not from the application, so application is free to accept further commands.
IPP:
Printing over the Internet or intranet using the Internet Printing Protocol. Printing over the internet is very popular these day. I'll explain it later in a new post.
E-Mail:
With this function, a print job can be e-mailed to a remote printer, such as over the Internet, using the standard print function in any Windows application.
NetBEUI:
Peer to Peer printing using the NetBEUI protocol. Printers are available in Network Neighborhood.
Windows Printer Sharing:
Printing to a shared network printer which is configured on another Windows machine.

Dot-Matrix Printers

A dot matrix printer or impact matrix printer refers to a type of computer printer with a print head that runs back and forth on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter.
Dot-matrix technology uses a series or matrix of pins to create printed dots arrangedto form characters on a piece of paper. The speed at which a dot-matrix printer prints is measured in the number of characters it can produce per second. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copies and carbonless copies.
The print head mechanism pushes each pin into the ribbon, which then
strikes the paper. The original dot-matrix print heads had 7 pins, while newer,
letter-quality print heads use 24 pins to produce near letter quality (NLQ) documents. Each pin is driven forward by the power of a tiny electromagnet or solenoid, either directly or through small levers (pawls).
Dot-matrix printers are called impact printers because the printing mechanism physically strikes the page. The continual motion of the pins through the print head creates a ton of heat, so avoid touching the print head after printing a handful of pages or more. A hot print head can give you a nasty burn.
Papermoves through a dot-matrix printer using a tractor-feed mechanism. Spoked wheels located on each side of the paper feed mechanism move the paper. The spokes on the outer edges of the wheels fit into holes on the sides of specially designed continuous form paper. As the wheels turn, they pull the paper through the printer.
Because impact printers physically strike the page, you can use themto create multipart forms with ease.Many offices and government agencies use them for that very reason. Although impact printers have been replaced in most homes and offices by newer, sexier inkjet and laser printers , they still retain a substantial portion of the market in their niches.
Advantages:
1.They can print on multi-part stationary or make carbon copies
2. Low printing cost
3. They can bear envoiromental conditions.
4. Longlife

Disadvantage
1. Noise
2. Low resolution
3. Very limiter Color performance
4. Low speed

Printer Spooling Services Problems

As I described before, when a user prints a document, the print job creates a temporary file on the disk for the document being printer. After that the application can be used for other tasks and the system sends the temporary file to the print device.
In windows, the print spool service s responsible for managing the print environment. If yo can't delete a print job from the print queue than you many have a corrupt queue.
This problem may be solved by restarting the print spooler services.Follow these steps to perform the task:
1. Go to Start Menu
2. Control Pannel
3. Performance an maintinance
4. Administrator toools
Actually when you restart the printing spool services, you are going to reboot the printing envoiroment.
Sometimes, you may want to move the printer spooler folder. The folder location should be changed if you are facing printing problem in windows and there is no hardware problem. Also if you are running out of space on drive C, spool directroy should be moved to another partition. To change the spool dierctory:
1.Start Menu
2. Printer and Faxes
3. Choose file
4. Server properties
5. Click advance tab
6. Enter the path of the new spool folder

Printer Troubleshooting Tips

Printer troubleshooting should always be done by a professional, however simple problems can be solved with very little efforts. In this post I would like to share some tips which I have found very useful.
Check the simple stuff first
The first thing you want to do when you cannot print is to verify the simple stuff. Check the cable connections, power etc. Visually check the printer itself, make sure that the printer in "online". If you have selected wrong paper size while sending the print, it may fails to print.
Paper Jams
Another type of problems that occurs a lot is paper jams. If you experience a number of paper jams over and over again, then you may want to verify that you are using the correct type of paper for the printer Some printers are designed for a specific type of paper so it will not work on other types.
Every printer has its maintenance cycle. If your printer has reached the limit, you may need to replace some parts like feeding rollers etc to avoid paper jamming. Check the documentation of you printer and verify this issue.
Garbled or Corrupted output
If you experience corrupted output or any type, it is possible that the driver has gone corrupt or that you have wrong driver installed. Some types of documents need PCL drivers,check if your printer supports PCL.
one of the best ways to find out if you have a bad driver or if the application you are printing from is causing the problem is to print a test page. To print a test page go to the Control panel, Printers and Faxes, Right click the printer, choose properties, and click "Print test page".
If test page is not printed correctly than you should try to reinstall the driver.
Slow Printing
Many printer have spooling option. This function saves the print jobs to hard disk in a queue before
sending them to the printer. Consider spooling as the traffic
controller of printing—it keeps all the print jobs from trying to print
at the same time.If spooling is disabled you may face slow printing. Check the properties of the printer and ensure that it is enabled.

Inkjet Printer's Printing Problems

Inkjet printers are more complicated than dot-matrix printers. So you may face more problems as compared to dot-matrix. Most common problem are:
Unclear Images
If the ink cartridge is running low ink it will produce unclear images on the paper. The only solution is to change the cartridge. Refilling the cartridge may cause printing quality issues so it is better to avoid it.
Blank Printouts
There are two main caused of blank ptintouts:
1.Low ink level
2.Clogged nozzle of the ink cartridges
If the ink is at an acceptable level, the nozzles have probably become clogged. To unclog the nozzle, dip a cotton swab in
denatured alcohol and gently wipe away any dried ink.
Confetti Printouts
Printouts with ink speckles, or confetti, always indicate an
ink problem. Over time, ink can escape into the body of an inkjet printer, eventually
finding its way onto subsequent printouts. To fix or prevent speckling,
clean the insides of the printer with a damp cloth.
Wrong Colors in Printouts
Sometimes, a inkjet printers produce printing using the wrong color. Low ink may cause it, it the color cartridge are full than try to clean the nozzles with a cotton swab dippen in denatured alcohol.
Smudges on Printouts
Have you ever touched the printout before the ink has completely dried? Smudges on printouts are most often caused by the user touching the printout before the ink has dried. So be aware of it. You may also face this quality issue if printer is dirt or nozzles are worn-out. You must replace the worn-out nozzles because they can't be repaired.