Electrical computers and digital processing systems: memory – Addressing combined with specific memory configuration or... – Addressing extended or expanded memory
Reexamination Certificate
1996-07-01
2001-04-10
Nguyen, Than (Department: 2187)
Electrical computers and digital processing systems: memory
Addressing combined with specific memory configuration or...
Addressing extended or expanded memory
C711S003000, C711S101000, C711S147000, C711S148000, C358S003050, C358S296000, C707S793000
Reexamination Certificate
active
06216197
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an apparatus and a method for extending memory in a computer printer or other computer output device. More particularly, the present invention relates to an apparatus and a method for extending the memory in a computer printer or other output device using a computer network and a network file system protocol.
(2) Prior Art
In the computing industry, it has become quite common to use a computer network to extend available memory on computer systems. A computer network is the interconnection of two or more computer systems. The interconnection is accomplished through some network medium such as through radio waves, wires, fiber optic cables, etc. A network medium is used to send messages between the computer systems. The messages being sent between the computers conform to a specific form known as a protocol.
Network protocols have been used to extend the amount of memory available in a computer. For example, network protocols have been used to extend the space available for the file system storage of a computer. NFS (Network File System) protocol designed by Sun Microsystems, Inc. is one such network protocol. The method for extending available computer memory using a network is well known in the art.
As with computers, computer printers also require the use of memory. A computer printer is a device which transforms information from a computer system into markings on a physical medium such as on a sheet of paper. During the transformation of information, the printer may need additional memory. For example, processing of a complex document requires a substantial amount of memory. An example of a complex document includes, a document containing text with different font styles, different character size, drawings intermingled with text, etc. However, presently available laser printers or other continuous raster scan devices are equipped with limited memory space with no source of auxiliary memory. If a printer memory becomes full before the data to be printed is completely transferred to the printer, the printer will halt and typically produce an error message. Thus, the limitation on available memory leads to failures in printing.
Providing additional memory space is especially relevant for laser printers or other continuous raster scan devices which typically require that all bit mapped data representing a page to be printed is in memory. This is due to the fact that once a print engine of a printer begins operation, it runs at a constant speed and the print engine cannot stop or slow down to wait for additional bit mapped data to be provided.
Given that presently available printers have limited memory space, it is desirable to have a method and an apparatus for extending the amount of memory available to a printer using a network and a set of network protocols.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a method and an apparatus which are advantageously used in conjunction with a digital computer and a computer network to provide the effect of additional memory for a printer or other output device. The method and apparatus of this invention allows the computer printer or other computer output device to function with less than the maximum amount of real memory normally required by the printer or other output device in processing a complex print or related job.
Assuming the output device is a printer, providing additional memory is not an issue if the printer is equipped with a large enough memory to store data for an arbitrarily complex document for printing. However, providing a large amount of memory is expensive. If cost is to be limited, performance may be sacrificed. For example, given a complex document to print, if the printer memory has a limited amount of memory and becomes full before the data to be printed is completely transferred to the printer, the printer will halt and typically produce an error message. The present invention provides a lower cost higher performance alternative to the presently available printers by obviating the need for purchasing a printer with a large memory size and still providing a source of auxiliary printer memory if a need for additional memory arises.
According to the invention, when the printer runs low on the amount of memory available, a portion of real memory of the printer containing infrequently used data is copied through a network to a computer's file system storage. The portion of the real memory containing the infrequently used data is then cleared and made available for other uses by the printer. When the piece of memory that was previously copied through the network is subsequently needed, it is copied through the network back into the printer's real memory.
As will be seen from the description which follows, the copying of memory into and out of the computer printer memory will allow the printer to function as if it had additional auxiliary memory.
REFERENCES:
patent: 5050098 (1991-09-01), Brown, III et al.
patent: 5159681 (1992-10-01), Beck et al.
patent: 5471564 (1995-11-01), Dennis et al.
Rocchetti Robert J.
Yacoub Yousef
Blakely & Sokoloff, Taylor & Zafman
Nguyen Than
Sun Microsystems Inc.
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