Browse Prior Art Database

Method for Achieving Display/Printer Independence on a Shared Printer

IP.com Disclosure Number: IPCOM000041956D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 74K

Publishing Venue

IBM

Related People

Heath, RT: AUTHOR [+4]

Abstract

This disclosure pertains to a communication system in which a plurality of processors and displays share a printer. Formatting of the printer is controlled by means of commands such as Set Vertical Format which contains the parameters, Maximum Print Line (MPL), Top Margin (TM), Bottom Margin (BM), and an arbitrary amount of vertical tab stops. It is desirable for the displays to be able to establish their own set of formatting parameters to accommodate screen copy printout, without requiring the processor to retransmit its format parameters with each print job. This new method allows the display to save the existing set of format parameters at the printer, to set and utilize any set of format parameters which it desires, and when finished, to restore the saved set of format parameters.

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Method for Achieving Display/Printer Independence on a Shared Printer

This disclosure pertains to a communication system in which a plurality of processors and displays share a printer. Formatting of the printer is controlled by means of commands such as Set Vertical Format which contains the parameters, Maximum Print Line (MPL), Top Margin (TM), Bottom Margin (BM), and an arbitrary amount of vertical tab stops. It is desirable for the displays to be able to establish their own set of formatting parameters to accommodate screen copy printout, without requiring the processor to retransmit its format parameters with each print job. This new method allows the display to save the existing set of format parameters at the printer, to set and utilize any set of format parameters which it desires, and when finished, to restore the saved set of format parameters. This method further allows the current set of parameters to be saved at the host processor, termed the primary. These may subsequently be returned to the printer, termed the secondary. In this manner, multiple host application programs may share a printer session without compromising each other's print formats. Parameters currently in use are stored together in a variable length register 1 termed the Current Format Parameter Control Block (FPCB), as shown in the figure. The register 1 contains all the parameters necessary to format a page. Vertical formatting parameters, such as Maximum Print Line, Top Margin, Bottom Margin, vertical tab stops and horizontal formatting parameters, Maximum Print Position, Left Margin, Right Margin, and horizontal tab stops, are contained in register 1. Also included would be additional parameters such as line density and print character density. The current FPCB is updated during the course of data transmission in accordance with parametric values determined during the decoding of format commands. The FPCB contains all the information necessary to save and restore all the parameters which the secondary supports. After a save and restore operation of any FPCB, either at the primary or the secondary, the format parameters then in effect will be precisely those in effect prior to the start of the save/restore operation for the designated FPCB. The saving and restoring of formats are controlled by means of a structured field, i.e., formatted message, which contains the following fields: Further discussion will concern the hardware embodiment of the disclosure, which is shown in the figure. The Save/Restore structured field is received via a communication link and is stored in the SRF Command Register 6, by means of a transfer from the Receive Data Buffer 7. Command Register 6 is n-bytes long to accommodate the variable length FPCB. At power-on time the current FPCB register 1 is initialized to defaul...