Background of the invention The current PCL5 Page Description Language provides functionality to select input media supplies via a standard escape sequence containing a numeric supply ID. A different supply can be used for any page in the job. This functionality is available on most third party PCL5 client print drivers. Each logical supply ID number is associated with a specific physical media supply on the respective device.

The functionality introduces device dependence between the job stream and the destination device because the IDs associated with the physical media supplies change from device to device. That is, the same job may cause media to be pulled/output to differing physical supplies depending on the device it is printed on. Currently, the only way to guarantee correct results is to edit or re-generate the print job.

Most PCL5 print drivers supporting media supply selection support a limited number of supply IDs, typically between I and 8. This becomes a significant limitation when devices have more than 8 physical media supplies.

Also, when submitting a legacy (archived) job stream or mainframe generated job to a device, it is necessary to have the physical media supplies configured as they were when the print job was initially created. Otherwise, incorrect supplies may be utilized for the job.

Summary of the invention This invention provides the ability to map the logical supply ID number specified within a job stream to any of the physical media supplies on a destination

device. This can be accomplished via a device level configuration tool or a job level command within the job stream.

The invention is achieved through a lookup table, typically embedded in software, which maps a logical supply ID number to any respective physical media supply on the device. This lookup table is examined for each occurrence of the logical supply command within the job stream. The lookup table is dynamic based on current device and job level settings.

The invention enables a customer to take any existing job, which contains requests for media supplies by ID, and configure the exact behavior based on the current destination device physical media supply configuration, without modifying the original job.

The invention has the capability when appropriate to select media from different media supply modules, each of the modules having a plurality of available media. For example, a supply module may be added to a printer which, in a "standard"configuration, lacks the capacity to provide a sufficient variety of media.

Brief description of the drawings Figure 1 is a flow chart setting out a process for selecting media.

Detailed description of the preferred embodiments This invention pertains to the printing of a job originating at an input device such as a computer or word processor. Currently, the input device communicates with a destination device such as an electronic marking machine or printer using a software job stream in a Page Description Language (PDL) such as PCL5, providing commands which pertain to the text and format of a document.

Specifically, the format commands include instructions as to a media source, in particular a media supply. Sometimes, it may be required that more than one type of media may be used; media may be paper or transparency media, and may vary according to size, color and weight, for example. Furthermore, paper media may be supplied as sheets or from rolls. If different pages of sections

of a document require different media types, commands are appropriately included in the job stream. However, job streams are currently configured so that they conform to a given destination device. In other words, a job configured for one printer cannot readily be transferred to another printer which is non-identical. In particular, each printer has its own source (supply) IDs. When it is attempted to print on a second printer a job designed for a first printer, either the job may not be printed or errors may occur. Hitherto, it has been necessary for an expert to convert the software so that the second printer can accept and print the job free of error.

The present invention provides that a non-expert user can, with a few keystrokes, enable the job-stream to incorporate commands necessary to print the job error-free. A logic control unit (LCU) incorporated in the destination device may include a digital computer, and has a stored program for sequentially acting on incoming commands.

In particular, the stored program includes a lookup table, which maps an unvarying logical supply ID against to a physical media supply which can vary according to the particular job or input device. At any point in the job-stream when a specific media supply needs to be identified, the lookup table is invoked to match the logical supply ID with the desired physical media supply. The lookup table is then not invoked again until a change in media is required.

In simple jobs wherein a document is printed entirely from a single type of media, only one logical supply ID and one corresponding physical media supply are used. In jobs which require more than one type of media, the lookup table contains an array of different logical supply IDs and their physical media supply counterparts. A user can key in an appropriate lookup table either at the destination device, or at the job level wherein the table can be keyed in at the input device.

The invention is used as follows, as indicated in the flow chart of Figure 1.

An operator constructs the lookup table to associate logical supply IDs with physical media supply. On the provision of a suitable command, the PCL5 job stream is communicated to the LCU, wherein it is parsed. When a logical supply

ID request is detected in the job stream, it is mapped to its physical media supply counterpart, as required by the predetermined lookup table, causing the appropriate physical media supply to be selected.

When it is desired to employ a second non-identical destination device, the operator constructs an appropriate lookup table, then proceeds as before. Of course, the accuracy of the lookup table depends on the supplies being correctly loaded, but this is always the case with any print job.

Typically, a lookup table can be factory-installed in a printer so that it provides for a default relationship between physical media supplies and logical supply IDs. This of course does not preclude the user from departing from the default setting and a newly selected setting. For example, the factory default table can be: Physical Printer Supply (6 trays) Logical Supply ID 1 1 2 2 3 3 4 4 5 5 6 6 and the user selected table can be:

Physical Printer Supply (6 trays) Logical Supply ID 1 1 2 7 3 10 4 4 5 5 6 6 This user-selected table can be chosen as a new default table.

It is a great advantage of this invention that it renders unnecessary any drastic changes to the software associated with archived jobs. This can represent a considerable saving of time and expense on the part of the user, as well as greatly expanding the user's flexibility in choice of printers. If the user is dissatisfied with a particular printer, and would prefer a new non-identical printer, the inclusion of the invention in the new printer obviates the necessity of extensively modifying the software, and removes a great disincentive to installing the new printer.

The present invention has been described in connection with certain embodiments, but it is not intended to limit the scope of the invention to the particular form set forth; on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.