CA1186417A - Shared resource clustered printing system - Google Patents
Shared resource clustered printing systemInfo
- Publication number
- CA1186417A CA1186417A CA000404544A CA404544A CA1186417A CA 1186417 A CA1186417 A CA 1186417A CA 000404544 A CA000404544 A CA 000404544A CA 404544 A CA404544 A CA 404544A CA 1186417 A CA1186417 A CA 1186417A
- Authority
- CA
- Canada
- Prior art keywords
- memory
- processor
- bit streams
- character
- scan
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- 230000001419 dependent effect Effects 0.000 claims 1
- 238000012545 processing Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 6
- 230000009466 transformation Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 230000001174 ascending effect Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- HFGHRUCCKVYFKL-UHFFFAOYSA-N 4-ethoxy-2-piperazin-1-yl-7-pyridin-4-yl-5h-pyrimido[5,4-b]indole Chemical compound C1=C2NC=3C(OCC)=NC(N4CCNCC4)=NC=3C2=CC=C1C1=CC=NC=C1 HFGHRUCCKVYFKL-UHFFFAOYSA-N 0.000 description 1
- 238000007476 Maximum Likelihood Methods 0.000 description 1
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- 238000007726 management method Methods 0.000 description 1
- 238000012015 optical character recognition Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/12—Digital output to print unit, e.g. line printer, chain printer
- G06F3/1297—Printer code translation, conversion, emulation, compression; Configuration of printer parameters
Abstract
ABSTRACT
The present invention is concerned with a character input device, a disc memory, an output marker, and a character generator for converting byte format character information into an output marker bit stream format, and for allocating the converted bit streams onto the disc memory. The stored bit streams can then be retrieved to directly drive the output marker or to be re-allocated onto the disc memory (after merging with presently converted bit streams if appropriate). In another feature of the invention, the converted or generated bit streams are represented in a compressed form (described by a four bit run length code). These bit streams in the compressed form can be merged by the character generator directly into this compressed form without having to first decompress the bit streams, merge, and then compress again.
Also printing systems can be configured using one or more character gene-rators committed to one or more disc memories, and in turn, each disc memory can drive one or more printers.
The present invention is concerned with a character input device, a disc memory, an output marker, and a character generator for converting byte format character information into an output marker bit stream format, and for allocating the converted bit streams onto the disc memory. The stored bit streams can then be retrieved to directly drive the output marker or to be re-allocated onto the disc memory (after merging with presently converted bit streams if appropriate). In another feature of the invention, the converted or generated bit streams are represented in a compressed form (described by a four bit run length code). These bit streams in the compressed form can be merged by the character generator directly into this compressed form without having to first decompress the bit streams, merge, and then compress again.
Also printing systems can be configured using one or more character gene-rators committed to one or more disc memories, and in turn, each disc memory can drive one or more printers.
Description
, The present invention relates to a printing system for con;verting character coded data into bit streams and for allocating converted (generated) bit streams onto a dis¢ memory, in particular, for later retrieval of the bit 5 streams from the memory to directly drive an output marker, for retrieval to merge the bit streams with presently converted bit streams to drive an output marker, or for retrieval of the bit streams to be merged with presently converted bit streams for allocation onto the disc memory for driving an output marker at a later time.
In prior art printing systems, such as the Xerox 9700 Laser Printer, it is common to store character coded binary information in a memory such as a disc. A character generator then converts the character coded in~ormation (one byte per character); into binary information (bit streams) suitable for driving an output marker such as a laser to print the character information. A
15 difficulty with this type of system, is that the character generator is on line, and the character generator must be geared or sized to peak demand. In addition, full pages or multiple pages cannot be completely generated before the output marker is committed to print.
It would be desirable, therefore, to provide a character generator 20 that can be sized to the average demand rather than the peak demand. It would also be desirable to provide a character generator that can convert the character coded information into bit streams and can allocate the converted bit streams to a disc rather than directly to the output markel, permitting fullpages, dense or complex pages, or sets of pages to be completely generated 25 before the marker is committed to print them. In other words, it would be desirable to provide a character generator that can store eonverted (generated) bit streams for later retrieval to directly drive an output marker, for later retrieval to merge the converted bit streams with presently con-verted bit streams to immediately drive an output marker, or for later 30 retrieval to be merged with presently ~onverted bit streams for allocation onto the disc for driving an output marker at a later time.
It would also be desirable to provide a character generator that can directly merge bit streams in compressed format without having to first decompress the bit streams, merge, and then compress again. ~i addition, it 35 would also be desirable to provide a printing system wherein one or more ., _ ~
In prior art printing systems, such as the Xerox 9700 Laser Printer, it is common to store character coded binary information in a memory such as a disc. A character generator then converts the character coded in~ormation (one byte per character); into binary information (bit streams) suitable for driving an output marker such as a laser to print the character information. A
15 difficulty with this type of system, is that the character generator is on line, and the character generator must be geared or sized to peak demand. In addition, full pages or multiple pages cannot be completely generated before the output marker is committed to print.
It would be desirable, therefore, to provide a character generator 20 that can be sized to the average demand rather than the peak demand. It would also be desirable to provide a character generator that can convert the character coded information into bit streams and can allocate the converted bit streams to a disc rather than directly to the output markel, permitting fullpages, dense or complex pages, or sets of pages to be completely generated 25 before the marker is committed to print them. In other words, it would be desirable to provide a character generator that can store eonverted (generated) bit streams for later retrieval to directly drive an output marker, for later retrieval to merge the converted bit streams with presently con-verted bit streams to immediately drive an output marker, or for later 30 retrieval to be merged with presently ~onverted bit streams for allocation onto the disc for driving an output marker at a later time.
It would also be desirable to provide a character generator that can directly merge bit streams in compressed format without having to first decompress the bit streams, merge, and then compress again. ~i addition, it 35 would also be desirable to provide a printing system wherein one or more ., _ ~
-2~
character generators can be allocated to one or more disc memories and each disc memory can be allocated to one or more printers.
Therefore, an o~ect of an aspect of the present invention to provide a new and improved printing system that is flexible, that can operate off-line or on-line~
that can allocate converted bit streams onto a disc memory, and that can retrieve the converted bit streams to direct-ly drive an output marker or to merge with presently con-verted bit streams. An object of an aspect of the presentinvention is to provide a chaxacter generator that can process very dense or c.omplex pages as several component pages merged together in successive pas~es and that can treat overlay text, forms and images that are preprocess-ed and stored on disc as component pages to be merged with current variable.text. ~n object of an aspect of the present invention is to proYide a character genera-tor that can directly merge compressed bit streams into compressed format.
Furtl.ler advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will ~e pointed out with particularity in the claims annexed to and forming a part o~ this specification~
Briefly~ the present invention in one aspect is concerned with a character input de~ice, a disc memory, an output marXer~ and a character generator for converting byte format character information into an output marXer bit stream format, and for allocating the converted bit streams onto the disc memory. The stored bit streams can then be retrieved to directly drive the output marker or to be re-allocated onto the disc memory ~after merging with presently converted bit streams if appropriate) for driving the output marker at a later timeO In another -2a-feature of the invention, the converted or generated bit st.reams are repres~nted in a compressed form [described by a ~our bit run length code). These bit streams in the compressed form can be merged by the character generator directly into compressed form without having to first decompress the bit streams, merge, and then compress again.
Also printing systems can be configured using one or more character generators committed to one or more disc memories, and in turn, each disc memory can drive one or more printers.
Other aspects of this invention are as follows:
In an apparatus for generating characters to be scanned in raster format from character input byte information, the combination of:
a character input device providing character 5 input byte information, a disc memory, a character generator connected to the input device and the disc memory for converting the character input byte information into bit streams, and bit streams 0 being allocated onto the disc memory, a buffer memory, a buffer memory bus, an output marker connected to the disc memory, the buffer memory including a plurality of buffer memory modules, the buffer memory bus including a plurality of buses, each of the rnemory modules being interconnected to one of the plurality of buses, the character generator including a processor memory and control processor, the control processor con-nected to the character input device for sorting the character input into scan line lists, a scan processor, the scan processor being connected to the control processor and transforming the scan line lists into run length coded field streams, and a merge processor intexconnected to the buffer memory modules and the disc memory through the plurality of buses, the merge processor for forming overlays, the processor memory lncluding a control memory, a scan memory, a font memory and a text memory, the scan -2b-memory and the font memory connected to the scan processor through a first processor memory bus7 the control memory, the scan memory, and the text memory being intexconnected through a second processor memory bus, the second processor memory bus being connected to the control processor and a third processor memory bus, the third processor memory bus interconnecting the control memory, the font memory, the text memory and the merge processor, the second processor memory bus being independent of the thir~
processor memoxy bus whereby cha.racter input byte information is converted into marker output format and stored in the disc memory for conveyance to the output marker.
An apparatus for generating characters to be scanned in raster format from character input byte information including:
a character input device providing the input byte information, a first memory for storing character input byte 0 information, a character generator communicating with the memory, a buffer memory, a buffer memory bus connectecl to the buffer mernory and the memory storing the input byte information, and an output marker, the olltput marker connected to the character generator, the character generator including a control processor connected to the character input device for sorting the character input byte information and a scan processor interconnected to the buffer memory and the first memory through the memory bus, the control processor providing scan line lists from the byte information, th~
scan processor transforming the scan li~e lists in~o coded field strings, the coded field strings providing an output ..7 -2c-mar~er scanning format whereby character input byte information is converted into output marker scanning format and stored in the first memory for directly driving the output marker.
The method of operat.ing a character generator having a processor, the character generator driving an output marker in a printing system comprising the steps of:
(a) converting character coded input data into bit streams in the processor;
(b) allocating the convexted bit streams into a memory;
.(c) merging the retrieved bit streams with other currently converted bit streams in the processor;
(d) allocating the merged bit streams onto the memory; and (e) retrieving the converted bit streams from ~he memory to drive the output marker.
BRIEF DESCRIPTION OF TXE DRAWINGS
Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to ~r, ~
the drawings wherein the same reference numerals have been applied to like parts and wherein:
Figure 1 is a general block diagram of the printer system incor-porating the present invention;
Figure 2 is a block diagram of the character input element of Figure l;
Figure 3 is a block diagram of the printing system of Figure l;
Figure 4 is a general block diagram showing the information flow in accordance with the present invention;
Figure S is a block diagram of the character generator shown in ~igure 4 in accord~nce with the present invention;
Figure 6 is a general flow chart showing the character generation process in accordance with the present invention;
Figure 7 is a flow chart illustrating the character generating process; and Figure 8 illustrates a printing system comprising a plurality of interconnected printers, discs, and character generators in accordance with the present invention.
With reference to Figure 1, there Ls shown a generalized block 29 diagram of a printing system including a charaeter or information input element 10, a character generator 12, and a configured printer connected to communication channel 16~ As will be illustrated in more de~ail, the input source to the printing system can be via the communication channel 16 or Yia an input scanner provided as an integral part of the printer 14~ The output OI
printin~ system can be the communication channel 16 or an output marker provided as an integral part OI the printer 14-With reference to Figure 2, the information input element 10 is interconnected to the communication channel 16 through an input element interface 180 Preferably9 the information input element 10 ineludes a mag tape 20 or any other suitable non-volatile storage media connected to buffer memory bus 22 through suitable interfaee 24. The mag tape interface 24 consists of the logic and circuits to operate the mag tape9 accept the formatted data and to load the data to the serial/parallel 64K buffer memory 26. The buffer memory 26 provides short term storage for input/output and
character generators can be allocated to one or more disc memories and each disc memory can be allocated to one or more printers.
Therefore, an o~ect of an aspect of the present invention to provide a new and improved printing system that is flexible, that can operate off-line or on-line~
that can allocate converted bit streams onto a disc memory, and that can retrieve the converted bit streams to direct-ly drive an output marker or to merge with presently con-verted bit streams. An object of an aspect of the presentinvention is to provide a chaxacter generator that can process very dense or c.omplex pages as several component pages merged together in successive pas~es and that can treat overlay text, forms and images that are preprocess-ed and stored on disc as component pages to be merged with current variable.text. ~n object of an aspect of the present invention is to proYide a character genera-tor that can directly merge compressed bit streams into compressed format.
Furtl.ler advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will ~e pointed out with particularity in the claims annexed to and forming a part o~ this specification~
Briefly~ the present invention in one aspect is concerned with a character input de~ice, a disc memory, an output marXer~ and a character generator for converting byte format character information into an output marXer bit stream format, and for allocating the converted bit streams onto the disc memory. The stored bit streams can then be retrieved to directly drive the output marker or to be re-allocated onto the disc memory ~after merging with presently converted bit streams if appropriate) for driving the output marker at a later timeO In another -2a-feature of the invention, the converted or generated bit st.reams are repres~nted in a compressed form [described by a ~our bit run length code). These bit streams in the compressed form can be merged by the character generator directly into compressed form without having to first decompress the bit streams, merge, and then compress again.
Also printing systems can be configured using one or more character generators committed to one or more disc memories, and in turn, each disc memory can drive one or more printers.
Other aspects of this invention are as follows:
In an apparatus for generating characters to be scanned in raster format from character input byte information, the combination of:
a character input device providing character 5 input byte information, a disc memory, a character generator connected to the input device and the disc memory for converting the character input byte information into bit streams, and bit streams 0 being allocated onto the disc memory, a buffer memory, a buffer memory bus, an output marker connected to the disc memory, the buffer memory including a plurality of buffer memory modules, the buffer memory bus including a plurality of buses, each of the rnemory modules being interconnected to one of the plurality of buses, the character generator including a processor memory and control processor, the control processor con-nected to the character input device for sorting the character input into scan line lists, a scan processor, the scan processor being connected to the control processor and transforming the scan line lists into run length coded field streams, and a merge processor intexconnected to the buffer memory modules and the disc memory through the plurality of buses, the merge processor for forming overlays, the processor memory lncluding a control memory, a scan memory, a font memory and a text memory, the scan -2b-memory and the font memory connected to the scan processor through a first processor memory bus7 the control memory, the scan memory, and the text memory being intexconnected through a second processor memory bus, the second processor memory bus being connected to the control processor and a third processor memory bus, the third processor memory bus interconnecting the control memory, the font memory, the text memory and the merge processor, the second processor memory bus being independent of the thir~
processor memoxy bus whereby cha.racter input byte information is converted into marker output format and stored in the disc memory for conveyance to the output marker.
An apparatus for generating characters to be scanned in raster format from character input byte information including:
a character input device providing the input byte information, a first memory for storing character input byte 0 information, a character generator communicating with the memory, a buffer memory, a buffer memory bus connectecl to the buffer mernory and the memory storing the input byte information, and an output marker, the olltput marker connected to the character generator, the character generator including a control processor connected to the character input device for sorting the character input byte information and a scan processor interconnected to the buffer memory and the first memory through the memory bus, the control processor providing scan line lists from the byte information, th~
scan processor transforming the scan li~e lists in~o coded field strings, the coded field strings providing an output ..7 -2c-mar~er scanning format whereby character input byte information is converted into output marker scanning format and stored in the first memory for directly driving the output marker.
The method of operat.ing a character generator having a processor, the character generator driving an output marker in a printing system comprising the steps of:
(a) converting character coded input data into bit streams in the processor;
(b) allocating the convexted bit streams into a memory;
.(c) merging the retrieved bit streams with other currently converted bit streams in the processor;
(d) allocating the merged bit streams onto the memory; and (e) retrieving the converted bit streams from ~he memory to drive the output marker.
BRIEF DESCRIPTION OF TXE DRAWINGS
Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to ~r, ~
the drawings wherein the same reference numerals have been applied to like parts and wherein:
Figure 1 is a general block diagram of the printer system incor-porating the present invention;
Figure 2 is a block diagram of the character input element of Figure l;
Figure 3 is a block diagram of the printing system of Figure l;
Figure 4 is a general block diagram showing the information flow in accordance with the present invention;
Figure S is a block diagram of the character generator shown in ~igure 4 in accord~nce with the present invention;
Figure 6 is a general flow chart showing the character generation process in accordance with the present invention;
Figure 7 is a flow chart illustrating the character generating process; and Figure 8 illustrates a printing system comprising a plurality of interconnected printers, discs, and character generators in accordance with the present invention.
With reference to Figure 1, there Ls shown a generalized block 29 diagram of a printing system including a charaeter or information input element 10, a character generator 12, and a configured printer connected to communication channel 16~ As will be illustrated in more de~ail, the input source to the printing system can be via the communication channel 16 or Yia an input scanner provided as an integral part of the printer 14~ The output OI
printin~ system can be the communication channel 16 or an output marker provided as an integral part OI the printer 14-With reference to Figure 2, the information input element 10 is interconnected to the communication channel 16 through an input element interface 180 Preferably9 the information input element 10 ineludes a mag tape 20 or any other suitable non-volatile storage media connected to buffer memory bus 22 through suitable interfaee 24. The mag tape interface 24 consists of the logic and circuits to operate the mag tape9 accept the formatted data and to load the data to the serial/parallel 64K buffer memory 26. The buffer memory 26 provides short term storage for input/output and
3~ data manipulation.
.7 A keyboard/display unit 28 is also connected to bus 22 via a keyboard/display interface 30. The keyboard/display interface 30 consists of logic and ¢ircuitry to maintain communication with an operator and to receive and present data. The information input element control processor 32 with related 8K x 16 RAM 34 provides the processing intelligence, timing7 and control sequences. The information input element 10 accepts coded input data from an input source, converts the data to suitable codes and creates appropriate packets o~ ir,formation to be forwarded to the charater generator 12.
~ a sample embodiment with reference to Figure 3, a configured printer 14 is connected to channel 16 via printer interface 36. An input scanner4D2 for scanned forms input operations is connected to the memory bus 40 through a scanner buffer run length compressor 46. Preferably, the input scanner 44 covers a 9" x 14" raster scan at 480 lines per inch resolution.
Scanning is assumed along the 14" side while documents are fed along the 9"
side (landscape feed). An output marker 38, for example, a laser device, is connected to buffer memory bus 40 through a marker bufIer run length decompressor 42. The output marker covers a 9" x 14" raster scan area at 480 lines per inch resolution. It should be understood, however, that many other suitable scanner and output markers are contemplated with various degrees of resolution. The output scanning is synchronous with the input scanning or is controlled by format information derived from the received digital data stre~m. Scanning is also in the landscape feed format. The memory bus 40 connects to a 64K bit buffer memory 48 and the memory 48 is also connected to the printer interface 36 via buffer memory bus 50.
The configured printer 14 also includes a control processor 52 with 4K x lB memory 54 connected to a manual input 56, a display 587 and the printer interface 36. It should be noted that the configured printer 14 may include one or more of the printers illustrated in Pigure 3 and that there may be variations of the printer illustrated in Figure 3. For example7 if the printer is to serve only a digital printing function, the input scanner 44 and associated compressor 46 can be eliminated.
The character generator 12 as shown in ~igures 1 and 4, in accordance with the present invention, accepts the input imormation in the coded character text line form generated by data processing systems or from other systems such as word processing and optical character recognition. It converts these documents to a raster form and forwards these raster docu-ments to the configured printer 14.
In particular, information enters in the form of character coded tapes, directly from a computer~ a modem or any other communication 5 interface. It is reforrnatted by the information input element 10 and forwarded to the character generator 12. The character generator 12 builds imaginal pages (blocks of data bits for directly modulating a raster scanning element such ~s A laser to reproduce the input information~. These blocks of data bits are stored upon the character generators associated disc memory 60 1~ or forwarded directly to the printer 14. The printer 14 receives the imaginalpages as if they came from a typical scanner and prints them in the normal fashion. The character generator 12 in general per~orms several functions.
~or example, it takes simple graphics or p~ge form description, either in coded data or in system standard coded compressed raster bit streams, pre-processes 15 the forms into appropriate run-length coded raster bit streams, and stores them in disc memory for later page formatting use.
It also takes textual information in coded characters communica-tion (orthographical) from a source on channel 16 and accumulates them as a document in its disc memory 60. ~ addition, it transforms the textual 20 information of a document thus stored in the disc mernory into formatted pages of images of appropriately coded, compressed raster bit streams.
Features of the transformation include multiple fonts on a page, proportional character spacing, and forms merging. The compre~sed font images are previously stored in the disc storage. The character generator 12 transmits the 25 transformed pages, one at a time, via channel 16 to the printer 14 for multiple copy printing.
In particular, with reIerence to Figure 4, the charac~er generator 12 converts the character coded input information into bit streams (referred to as converted or genera$ed bit streams~. ~ general, the input to the character 30 generator 12 can be via a communication interface or via ~n input scanner.
These generated bit streams are allocated onto the disc memory B0, as illustrated by the arrow in Figure 4. The generated bit streams can then be retrieved from the disc memory 60 (retrieved bit stream3 and immediately conveyed to an output deviee. In general, the output can be a communication 35 interface or an output marker such as configured printer 14.
The generated bit streams can also be retrieved by the character generator 12 to be merged with bit streams that are currently or presently being converted within character generator 12.
It should be understood, however, that merging could also include 5 two imaginal files or merging a file with formatting information such as a half tone dot format. For example, inrormation such as overlay text, forms, or images that has already been preprocessed and stored on the disc memory 60 as component pages can be merged with in~ormation being converted by the character generator 12 in the current pass or conversion. It should be noted 10 that currently converted bit streams means bit streams that are being converted in the character generator and not yet stored on the disc memory 60.
These merged blt streams can then be allocated onto the disc to be retrieved to immediately drive an output marker. Alternatively, the merged 15 bit streams can be stored onto the disc for use at a later time. It should benoted that pages or blocks of information can be partially processed and the bit streams stored on the disc in either a compressed or non-compressed mode.
This information can then be merged with additional page information and likewise stored in either compressed or non-compressed mode. This process 20 can be repeated by several iterative passes to store several sections or whole pages.
Figure 5 shows the character generator 12 in more det~il. In a specific embodiment, three processors are used. ln particular, a control processor 62 accepts page information from the informatis~n input element 10 25 and sorts it into the proper order for conversion from the character code to the raster scan code. The control processor 62 is the master processor controlling general housekeeping, resource management and allocation including disc space, communic~tion channel scheduling and control~ document processing scheduling and task creation, page text list proeessing including 30 font collection and scan line list (SLL) control.
A scan processor 64 is ~onfigured to transform the textual data of each scan line liæt -forwarded by the control processor 62 into run length codedfield streams (RFS)o An image or merge processor 66 merges forms as overlays (not handled by the eontrol processor 62 as part of the scan line list)35 and run length coded field streams with the test bit streams created by the scan processor 64. ~ short, the image or merge processor 66 combines raster forms and raster text or sections of dense pages with prior sections to form output pages compatible witll the printer 14. llle combined bit stream is then passed on to the compressor/decompressor 68.
The compressor consists of a two line maximum likelihood predic-tion, run length encoding and error propagation control logic. The prediction and run length encoding are performed on a line by line basis. The compressor 68 is responsible for converting the run length coded bit stream into the system standard coded run lengthidelta compression bit stream or any other suitnble compressed bit stream, and loading the resulting data into an assigned memory module 74 under control of the image or merge processor 66.
The eharacter generator 12 o~ Figure 5 is shown connected to communication channel 16 preferably a 15 megabit per second bandwidth channel through a generator interface 70. The generator interface 70 includes the necessary communication circuitry to allow data transfer between the character generator 12 and the communication channel 16 including receive eircuitry 72a with buffer 72b and send circuitry 72c with buMer 72d.
~ a sample embodiment, each of the buffers 72b and 72d is a SK
bit RAM capable of operating at a 120 mega byte per second rate. It has the logic to interrupt the control processor 62 for service and to exchange data with memory modules 74 assigned by the control processor. There are two buffers 72b and 72d for alternate exchange and communication operations.
Information transmission on the communic&tion channel 16 is by packets. A
packet is logically formatted data bits contained between a header and trailer~
For data packets, the header and trailers are processed by the control processor while the data (up to 4K bit blocks) is exchanged with memory modules 74. Control packets are entirely processed by the control processor 62.
Preferably, the character generator 12 includes 64K bit buffer memory modules 74 conneeted to four memory bu~es 76, 78, 8û and û2. The ~uffer memory modules 74 are the intermediate information buffer between the disc memory 60 and other elements in the system. It is organized in 64K
bit modules. A module consists of storage ~or the 64K bit data pius appropriate error correcting code bits, storage timing, drive circuitry, addressing logic, and memory bus connection logie.
l~ach bufIer memory module 74 is a self contained operating unit7 dynamically assigned or switched by the control processor 62 to operate with one of the four memory buses. Data timing is synchronized with the current user element's operation timing. The assigment stays with the user element until terminated by the user or because the appropriate amount OI data has been exchanged. Upon termination, the control processor 62 is notified immediately via a program interrupt. If processing or transforming operations are to be done by the processors, the information in the memory module ~4 is generally first transferred to RAM in the processor memory, before processing or transforming operations by the processors.
The memory module 74 data transfer bandwidth is capable of 60 mega bits per second (Mbps) rate. The transfer block size is nominally in 4K
bits or more. Each of the memory buses 76, 78, 80 and 82 is an aceess port by other system elements while sharing that port with buffer memory modules.
The buffer memory eonsists of memory module address, control signals, coders for generating error checking codes, decoders for error detection, and interface logic to memory modules. The disc memory 60 having a capacity of approximately 800 megabits is connected through a disc interface 8~ to memory bus 80. The disc 60 is preferably a 4-head parallel read/write configuration. This configuration of the disc unit consists of three platters having a net capacity of approximately 800 Mb. The disc interface 86 2û controls disc operation, and manages data transfer to and from the memory modules 74 selected by the control processor 62.
The processor memory 88 as shown within the dotte~ lines includes a 16K x 16 control memory 90, an 8K x 32 scan RAl~q 92, a 32K x 8 font RAM
94, ~n 8K x 16 text RAM 96, and an image RAM 98. The processor memory 88 is the control and/or working memory for the processors. It is organized in a structure of 4K ~ 32 bit word RAM modules. Each RAM module consists of the 128K bit data storage, plus appropriate error cormecting code bits7 timing and drive circuit, addressing logic and connection logic to two user access ports.
The processor memory modules are organized to respond to the 64K word addressing space of the processors. If there are more than one processor and more than 64K words of processor memory, each proeessol will have some private RAM modules alld shared RAM modules with another processor. Each RAM module is conversely accessible by the two processors.
~ this configuration, the total processor memory requirement is estimated at 64K words. To keep up with the processing bandwidth requirements of the processors, with minimum interference, memory modules are allocated such that a RAM module is predominantely accessed by only one processor at a time in the eourse of processing àata.
In accordance with another fe~ture of the present invention, an x 5 bit by y bit font character image is described in a list of run length 4 bit coded field strings (RFS), each field representing a sequence of one~ or zeros. Each string starts with ~ length field for a given or defined polarity. Each subsequent length field alternates representing zeros and ones unless a control or end code is encountered in the field. This description coYers the active lO zone of the vari~ble size (both in height and width) character.
In a specific embodiment, a 4 bit field was used as follows 0000 Control Code 0111 1 to 13 length 1110 Extension Code 1111 End Code The control code (0000) is interpreted as follows:
1. If foLlowed by a length field (such as 0001, or 1110), the length field indicates length for a field regardless of current polarity.
2. If ~llowed by an End Code (1111), the rest of the scan line should be filled with zeros.
3. II followed by another Control Code (0000), interpret the next field ~or up to 16 control functions. (Any length field thereafter corresponds to the current polarity.)
.7 A keyboard/display unit 28 is also connected to bus 22 via a keyboard/display interface 30. The keyboard/display interface 30 consists of logic and ¢ircuitry to maintain communication with an operator and to receive and present data. The information input element control processor 32 with related 8K x 16 RAM 34 provides the processing intelligence, timing7 and control sequences. The information input element 10 accepts coded input data from an input source, converts the data to suitable codes and creates appropriate packets o~ ir,formation to be forwarded to the charater generator 12.
~ a sample embodiment with reference to Figure 3, a configured printer 14 is connected to channel 16 via printer interface 36. An input scanner4D2 for scanned forms input operations is connected to the memory bus 40 through a scanner buffer run length compressor 46. Preferably, the input scanner 44 covers a 9" x 14" raster scan at 480 lines per inch resolution.
Scanning is assumed along the 14" side while documents are fed along the 9"
side (landscape feed). An output marker 38, for example, a laser device, is connected to buffer memory bus 40 through a marker bufIer run length decompressor 42. The output marker covers a 9" x 14" raster scan area at 480 lines per inch resolution. It should be understood, however, that many other suitable scanner and output markers are contemplated with various degrees of resolution. The output scanning is synchronous with the input scanning or is controlled by format information derived from the received digital data stre~m. Scanning is also in the landscape feed format. The memory bus 40 connects to a 64K bit buffer memory 48 and the memory 48 is also connected to the printer interface 36 via buffer memory bus 50.
The configured printer 14 also includes a control processor 52 with 4K x lB memory 54 connected to a manual input 56, a display 587 and the printer interface 36. It should be noted that the configured printer 14 may include one or more of the printers illustrated in Pigure 3 and that there may be variations of the printer illustrated in Figure 3. For example7 if the printer is to serve only a digital printing function, the input scanner 44 and associated compressor 46 can be eliminated.
The character generator 12 as shown in ~igures 1 and 4, in accordance with the present invention, accepts the input imormation in the coded character text line form generated by data processing systems or from other systems such as word processing and optical character recognition. It converts these documents to a raster form and forwards these raster docu-ments to the configured printer 14.
In particular, information enters in the form of character coded tapes, directly from a computer~ a modem or any other communication 5 interface. It is reforrnatted by the information input element 10 and forwarded to the character generator 12. The character generator 12 builds imaginal pages (blocks of data bits for directly modulating a raster scanning element such ~s A laser to reproduce the input information~. These blocks of data bits are stored upon the character generators associated disc memory 60 1~ or forwarded directly to the printer 14. The printer 14 receives the imaginalpages as if they came from a typical scanner and prints them in the normal fashion. The character generator 12 in general per~orms several functions.
~or example, it takes simple graphics or p~ge form description, either in coded data or in system standard coded compressed raster bit streams, pre-processes 15 the forms into appropriate run-length coded raster bit streams, and stores them in disc memory for later page formatting use.
It also takes textual information in coded characters communica-tion (orthographical) from a source on channel 16 and accumulates them as a document in its disc memory 60. ~ addition, it transforms the textual 20 information of a document thus stored in the disc mernory into formatted pages of images of appropriately coded, compressed raster bit streams.
Features of the transformation include multiple fonts on a page, proportional character spacing, and forms merging. The compre~sed font images are previously stored in the disc storage. The character generator 12 transmits the 25 transformed pages, one at a time, via channel 16 to the printer 14 for multiple copy printing.
In particular, with reIerence to Figure 4, the charac~er generator 12 converts the character coded input information into bit streams (referred to as converted or genera$ed bit streams~. ~ general, the input to the character 30 generator 12 can be via a communication interface or via ~n input scanner.
These generated bit streams are allocated onto the disc memory B0, as illustrated by the arrow in Figure 4. The generated bit streams can then be retrieved from the disc memory 60 (retrieved bit stream3 and immediately conveyed to an output deviee. In general, the output can be a communication 35 interface or an output marker such as configured printer 14.
The generated bit streams can also be retrieved by the character generator 12 to be merged with bit streams that are currently or presently being converted within character generator 12.
It should be understood, however, that merging could also include 5 two imaginal files or merging a file with formatting information such as a half tone dot format. For example, inrormation such as overlay text, forms, or images that has already been preprocessed and stored on the disc memory 60 as component pages can be merged with in~ormation being converted by the character generator 12 in the current pass or conversion. It should be noted 10 that currently converted bit streams means bit streams that are being converted in the character generator and not yet stored on the disc memory 60.
These merged blt streams can then be allocated onto the disc to be retrieved to immediately drive an output marker. Alternatively, the merged 15 bit streams can be stored onto the disc for use at a later time. It should benoted that pages or blocks of information can be partially processed and the bit streams stored on the disc in either a compressed or non-compressed mode.
This information can then be merged with additional page information and likewise stored in either compressed or non-compressed mode. This process 20 can be repeated by several iterative passes to store several sections or whole pages.
Figure 5 shows the character generator 12 in more det~il. In a specific embodiment, three processors are used. ln particular, a control processor 62 accepts page information from the informatis~n input element 10 25 and sorts it into the proper order for conversion from the character code to the raster scan code. The control processor 62 is the master processor controlling general housekeeping, resource management and allocation including disc space, communic~tion channel scheduling and control~ document processing scheduling and task creation, page text list proeessing including 30 font collection and scan line list (SLL) control.
A scan processor 64 is ~onfigured to transform the textual data of each scan line liæt -forwarded by the control processor 62 into run length codedfield streams (RFS)o An image or merge processor 66 merges forms as overlays (not handled by the eontrol processor 62 as part of the scan line list)35 and run length coded field streams with the test bit streams created by the scan processor 64. ~ short, the image or merge processor 66 combines raster forms and raster text or sections of dense pages with prior sections to form output pages compatible witll the printer 14. llle combined bit stream is then passed on to the compressor/decompressor 68.
The compressor consists of a two line maximum likelihood predic-tion, run length encoding and error propagation control logic. The prediction and run length encoding are performed on a line by line basis. The compressor 68 is responsible for converting the run length coded bit stream into the system standard coded run lengthidelta compression bit stream or any other suitnble compressed bit stream, and loading the resulting data into an assigned memory module 74 under control of the image or merge processor 66.
The eharacter generator 12 o~ Figure 5 is shown connected to communication channel 16 preferably a 15 megabit per second bandwidth channel through a generator interface 70. The generator interface 70 includes the necessary communication circuitry to allow data transfer between the character generator 12 and the communication channel 16 including receive eircuitry 72a with buffer 72b and send circuitry 72c with buMer 72d.
~ a sample embodiment, each of the buffers 72b and 72d is a SK
bit RAM capable of operating at a 120 mega byte per second rate. It has the logic to interrupt the control processor 62 for service and to exchange data with memory modules 74 assigned by the control processor. There are two buffers 72b and 72d for alternate exchange and communication operations.
Information transmission on the communic&tion channel 16 is by packets. A
packet is logically formatted data bits contained between a header and trailer~
For data packets, the header and trailers are processed by the control processor while the data (up to 4K bit blocks) is exchanged with memory modules 74. Control packets are entirely processed by the control processor 62.
Preferably, the character generator 12 includes 64K bit buffer memory modules 74 conneeted to four memory bu~es 76, 78, 8û and û2. The ~uffer memory modules 74 are the intermediate information buffer between the disc memory 60 and other elements in the system. It is organized in 64K
bit modules. A module consists of storage ~or the 64K bit data pius appropriate error correcting code bits, storage timing, drive circuitry, addressing logic, and memory bus connection logie.
l~ach bufIer memory module 74 is a self contained operating unit7 dynamically assigned or switched by the control processor 62 to operate with one of the four memory buses. Data timing is synchronized with the current user element's operation timing. The assigment stays with the user element until terminated by the user or because the appropriate amount OI data has been exchanged. Upon termination, the control processor 62 is notified immediately via a program interrupt. If processing or transforming operations are to be done by the processors, the information in the memory module ~4 is generally first transferred to RAM in the processor memory, before processing or transforming operations by the processors.
The memory module 74 data transfer bandwidth is capable of 60 mega bits per second (Mbps) rate. The transfer block size is nominally in 4K
bits or more. Each of the memory buses 76, 78, 80 and 82 is an aceess port by other system elements while sharing that port with buffer memory modules.
The buffer memory eonsists of memory module address, control signals, coders for generating error checking codes, decoders for error detection, and interface logic to memory modules. The disc memory 60 having a capacity of approximately 800 megabits is connected through a disc interface 8~ to memory bus 80. The disc 60 is preferably a 4-head parallel read/write configuration. This configuration of the disc unit consists of three platters having a net capacity of approximately 800 Mb. The disc interface 86 2û controls disc operation, and manages data transfer to and from the memory modules 74 selected by the control processor 62.
The processor memory 88 as shown within the dotte~ lines includes a 16K x 16 control memory 90, an 8K x 32 scan RAl~q 92, a 32K x 8 font RAM
94, ~n 8K x 16 text RAM 96, and an image RAM 98. The processor memory 88 is the control and/or working memory for the processors. It is organized in a structure of 4K ~ 32 bit word RAM modules. Each RAM module consists of the 128K bit data storage, plus appropriate error cormecting code bits7 timing and drive circuit, addressing logic and connection logic to two user access ports.
The processor memory modules are organized to respond to the 64K word addressing space of the processors. If there are more than one processor and more than 64K words of processor memory, each proeessol will have some private RAM modules alld shared RAM modules with another processor. Each RAM module is conversely accessible by the two processors.
~ this configuration, the total processor memory requirement is estimated at 64K words. To keep up with the processing bandwidth requirements of the processors, with minimum interference, memory modules are allocated such that a RAM module is predominantely accessed by only one processor at a time in the eourse of processing àata.
In accordance with another fe~ture of the present invention, an x 5 bit by y bit font character image is described in a list of run length 4 bit coded field strings (RFS), each field representing a sequence of one~ or zeros. Each string starts with ~ length field for a given or defined polarity. Each subsequent length field alternates representing zeros and ones unless a control or end code is encountered in the field. This description coYers the active lO zone of the vari~ble size (both in height and width) character.
In a specific embodiment, a 4 bit field was used as follows 0000 Control Code 0111 1 to 13 length 1110 Extension Code 1111 End Code The control code (0000) is interpreted as follows:
1. If foLlowed by a length field (such as 0001, or 1110), the length field indicates length for a field regardless of current polarity.
2. If ~llowed by an End Code (1111), the rest of the scan line should be filled with zeros.
3. II followed by another Control Code (0000), interpret the next field ~or up to 16 control functions. (Any length field thereafter corresponds to the current polarity.)
4. A control eode following an End Code denotes the end of the font RFS only.
35The End Code (llll) Indicates the end of the current font scan line.
(All unused fields after the End Code for the rest of word should be filled with End Codes.) The Extension Code (1110) in interpreted as a length ~xtension of the current polarity. It means that 13 is to be added to the length value of thenext field, keeping the current polarity. The extension code (1110) can be chained one after another ~or as long as needed. The interpretation of the
35The End Code (llll) Indicates the end of the current font scan line.
(All unused fields after the End Code for the rest of word should be filled with End Codes.) The Extension Code (1110) in interpreted as a length ~xtension of the current polarity. It means that 13 is to be added to the length value of thenext field, keeping the current polarity. The extension code (1110) can be chained one after another ~or as long as needed. The interpretation of the
5 RFS fields is the same for the scan lines of a transformed page. Thus, a blankline is represented by a control code (0000) followed by an l~nd Code (1111) in the RFS.
It should be understood that the above choice of field size and coding could be optimized with more study on the various types of fonts.
10 There are four such 4 bit fields to each 16 bit word. The first bit of each scan starts at a reference position. The first field o each scan line RFS representsa string OI ones, unless it is a control code. Each scan line s~arts at the beginning field of a half-word. The unused field of the last half-word of Q
scan line is filled wîth end code.
Font descriptions are previously stored in the character generator disc memory 60. It is assured that each font is described in two scan directions--short-side or portrait scan direction and long-side or landscape scan direction--to be selected for portrait or landscape mode of operation.
Composite font can be dynamically generated by the control processor 62 20 (with the help o~ image processor 66) and sorted as special font ~or later use.
Overlapping graphics or characters, when used repeatedly, can be handled in this manner. Forms and graphics are assumed to be previously described in the RFS format and stored in the disc memory.
For cert~in types of forms and graphics, they can be treated as if 25 they are a special eharacter font, described in exactly the same way as the text character fonts. Tn these cases, the form characters or graphics eharac-teristics are added into the scan line list tSLL~ by the control processor 62.
They are processed by the scan processor 64 along with the text character in the list. Other types of forms and graphics (complex images) that cannot be 30 treated as special character fonts will be treated as a complete page overlay.
Such overlays will be stored in R~S form~t on the disc memory 6û. The RF~
description of the overlay page is loaded into assigned memory modules 74 by the control processor 62.
The image processor 66 will read the overlay RFS from the 35 memory module 74 and merge it with the text RFS generated by the sean processor 64 in the image RAM 98. The merged RFS is then fed to the compressor 68 for transformation into the system standard coded raster bit stream for transmission to the printer 14 via the channel 16.
The image processor 66 merge operation is done by processing the two RFS in parallel, while keeping track of the scan line position, in the RFS
5 format. It is assumed that the complete overlay RFS description can be contained by a reasonable number of memory modules 74. While this is true, overlay merging has no effect on the transformation speed. Otherwise~
successive segments of the form overlay description have to be accessed from the disc memory 60 and transformation speed may degrade.
The document conversion process is best illustrated with respect to Figures 6 and 7. The content of the document is assumed to have been generated from another source on the com munication channel 16. The information input element lQ has obtained the document directly from either a host computer on-line or from a magnetic tape or other suitable device controlled by a computer (off-line).
The document description is previously transmitted and stored in the character generator disc memory 60. The document content is assumed to be a line by line format with control characters indicat;ng a selection of fonts, forms, and graphic addition. The content description is translated by the input 2~ element 10 from the host computer description to one that is understood by the character generator 12.
A character text to page image transformation by the three processors 62, 64 and 66 in the character generator 12 is then performed in the following sequence in accordance with the present invention.
Step 1. The document text is conveyed to the text RAM 96 and processed by the controll processor 620 In particular a page ~approximately 2000 characters) is extracted and listed in a character text list (CTL) in the text RAM 96. Each character in the CTL is described in four sixteen bit words containing the following information:
3S a. Controls - character code, font selection, scan offset from reference, and orientation.
b. X direction position of the character reference point.
c. Y direction position of the character reference point.
do font character starting word address in the font RAM 94.
llle character text list typically has 2K entries in the text RAM.
Pages of more than 2K characters are processed in 2K character segments.
There are at least two ways to process pages with more than 2K
characters. ~ one embodiment~ it is possible to pick a convenient se~ment of up to 2K random characters from the character text list (CTL). A complete run length coded field stream (RFS) overlay page ;s created into a serial parallel memory module 74 in the first pass. A second segment of 2K
characters is then processed and merged with the overlay from the Iirst pass into a new overlay. Thus, subsequent passes of 2K characters are merged with the overlay of the proceeding pass until all the characters of the page are processed and merged. This method requires as may 2K character passes as the number of 2K segments.
~ another embodiment, it is possible to presort the eomplete page by sorting it into vertical ~scan direction) strips of 2K character segments andstoring them onto the disc memory 60 or a memory module 74. ~uccessive strips are called in and processed in a continuous pass, starting from the left side of the page. This method takes only one long pass processing n by 2k characters. In general, the processing time is related to the number of characters on a page. It should be noted that the 2K threshhold is an arbitrary number. It should also be noted that only those fonts required by the CTL
need to be in the font RAM 94 when a page is processed in segments.
Step 2. The character text list (CTL) is next processed by the control processor 62 to extract those characters that are actively involved in the current scan and form an input scan line list (ISLL) in the scan RAM 92.
Assuming the scan is in the Y direction, the current scan is the ~th lîne acrossthe page~ Using a portrait page, the Y direction is along the long side, for example, Irom bottom to top and the X direction is along the short side9 for example, from left to right.
The first ISLL would eontain characters from the left verticle strip of the page for a certain number of sc~n lines ln the X direction. Each character in the ISLL is described by three 16 bit words as follows-l~ Currerlt forlt RFS starting word ~ddress. Note that the width of the character as well as the end o~ each scan line are denoted in the RFS itself(16 bits).
2. Y direction position of the ch~racter reference point (13 bits).
3. g direction position of the character refel~ence point at which the character should become acffvely processed. The character entries in the ISLL must be sorted by the control processor 62 in proper order. Namely, the characters to be processed by the æcan processor 64 for any line must be in ascending Y starting position order and new characters starting at later than the Xth line must be in ascending X starting positions of successive segments of adjacent characters. The ISLL is self-terminated by an entry in which the 5 font RFS address is all zeros.
Step 3. The ISLL is passed on by the control processor to the scan processor 64 for RFS generation. The scan processor keeps an alternating active scan line list (ASLL) in sean RAM 92. Each character in the active scan list (ASLL) is described by a double 16 bit word as follows:
1. Y starting position reference (13 bit) 2. Current font RFS starting word address (being updated for each Xth scan line) 16 Bits. Note that the width of the character as well as the end of each scan RFS, are denoted in the R~S content of the font.
The scan processor processes each char~cter entry from the 15 current ASLL and stores the updated entry of the same character in the alternative ASLL in succession. However, if the character font terminates (denoted by an end code 1111 folls)wed by a control code 0000), the entry is notstored thereby removing it from the ASLL.
Durin8~ the processing, the current X position is compared with the 20 ~ starting position of the next character of the ISLL to anticipate a new character starting in the next scan line. In that case, the ISLL character entryis stored into the ASLL. Thus, the alternate ASLL is updated with the proper character sequence for the next scan line. At the end of each scan line (terminated by an entry with the font RFS being all zeros), the alternate ASLL
25 and the current ASLL are exchanged.
RFS generation is a simple iteration process for each character entry in the ASLL done in the scan processor as follows 1. The current Y position is subtracted from the charaeter Y
starting position. If the result is negative, this character overlaps with the 30 last ~aracter. Ihe result normally is expected to be zero or positive. An appropriate number of zeros9 in RFS fields, is appended to the output RF~.
2. The font RFS of the character is then processed and appended to the output RFS one field at a time until an end code is detected. As this is done, the current Y position is advancedO
3O The font RFS address is updated be~ore storing the two word entry in the alternate ASLL.
4. The ne~ct e~try in the ASLL is accessed to repeat from Step l.
If the new entry access contains zeros as the font RFS address, the end of the ASLL is reached and an appropriate end code is appended, and the RFS
generation of the current scan line is complete.
When the RFS register has accumulated two 16 bit words of RFS, the two words are stored in the image RAM 98. These two words are stored using the current output RF5 address. Note that for a faster version9 the image RAM 98 could be structured as an FIFO store.
Step 4. The RFS in the image RAM 98 (or in the FIFO store) is passed on to the image processor 6fi for merging with any required overlay and for conversion into appropriate standard data compaction codes by the compressor 68. The final output is stored into its assigned buffer memory module 74. When a buffer memory module 74 is filled up, the control processor 62 is notified via a bufer memory program interruptO The control processor will then assign a new buffer memory module to the image processor. The control processor will also route the filled buffer memory module 74 to the next appropriate operation; namely, transmission to the printer 14, via the communication channel 16 for printing.
In accordance with the present invention, the merging process of two R~S's into one output RFS in a compressed form is done by the image processor 66. Starting from the beginning of the two RFS's, the current field OI one is compared with that of the other in the following manner:
Case 00/ll - Namely, both fields are denoting the same polarity:
The shorter field value with the appropriate polarity is passed onto the output RFS. 111e RFS having the shorter field value advances to the next field, with appropriate polarity updated. The other RFS is not advanced by its field value and decreased by the shorter field value. ~ case that the two field values are equal9 both RFS7s advance.
Case lO/Ol - Namely, the two fields are denoting opposite polarities:
The shorter field value is passed onto the output R~S with a 1 polarity. The RFS having the shorter field value adv~nces to the next field, with appropriate polarity updated. The other RFS is not advanced but its field value is decreased by the shorter field valueO
1~ case that the two field values are equal9 both RFS's advance.
Y~
The above Steps 1 to 4 repeat in this pipeline process;ng fashion for each 2K segment OI the page until the complete page i5 transformed and until the complete document is transformed.
With reference to Figure 8, there is shown an exemplary multiple 5 printing system in accordance with the present invention. A plurality of printers 14 are driven by a pair of disc memories 60. The disc memories 60 aPe connected to a plurality of character generators 12. Generation of characters onto the disc memories permits complete pages or page sets to be generated be~ore any printer is committed to reproduce the pages of text. It should be 10 noted that many other system configurations are possible but in partieular the character generators can be off line to convert the input character into raster scan format and can allocate the converted characters onto the disc for directly driving the printer or for retrieval and merging with current con-verted eharacters.
While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be appreciated that numerous changes and modifications are likely to occur to those skilled in the art, and it is intended in the appended claims to cover allthose changes and modifications falling within the true spirit and scope of the 20 present invention.
It should be understood that the above choice of field size and coding could be optimized with more study on the various types of fonts.
10 There are four such 4 bit fields to each 16 bit word. The first bit of each scan starts at a reference position. The first field o each scan line RFS representsa string OI ones, unless it is a control code. Each scan line s~arts at the beginning field of a half-word. The unused field of the last half-word of Q
scan line is filled wîth end code.
Font descriptions are previously stored in the character generator disc memory 60. It is assured that each font is described in two scan directions--short-side or portrait scan direction and long-side or landscape scan direction--to be selected for portrait or landscape mode of operation.
Composite font can be dynamically generated by the control processor 62 20 (with the help o~ image processor 66) and sorted as special font ~or later use.
Overlapping graphics or characters, when used repeatedly, can be handled in this manner. Forms and graphics are assumed to be previously described in the RFS format and stored in the disc memory.
For cert~in types of forms and graphics, they can be treated as if 25 they are a special eharacter font, described in exactly the same way as the text character fonts. Tn these cases, the form characters or graphics eharac-teristics are added into the scan line list tSLL~ by the control processor 62.
They are processed by the scan processor 64 along with the text character in the list. Other types of forms and graphics (complex images) that cannot be 30 treated as special character fonts will be treated as a complete page overlay.
Such overlays will be stored in R~S form~t on the disc memory 6û. The RF~
description of the overlay page is loaded into assigned memory modules 74 by the control processor 62.
The image processor 66 will read the overlay RFS from the 35 memory module 74 and merge it with the text RFS generated by the sean processor 64 in the image RAM 98. The merged RFS is then fed to the compressor 68 for transformation into the system standard coded raster bit stream for transmission to the printer 14 via the channel 16.
The image processor 66 merge operation is done by processing the two RFS in parallel, while keeping track of the scan line position, in the RFS
5 format. It is assumed that the complete overlay RFS description can be contained by a reasonable number of memory modules 74. While this is true, overlay merging has no effect on the transformation speed. Otherwise~
successive segments of the form overlay description have to be accessed from the disc memory 60 and transformation speed may degrade.
The document conversion process is best illustrated with respect to Figures 6 and 7. The content of the document is assumed to have been generated from another source on the com munication channel 16. The information input element lQ has obtained the document directly from either a host computer on-line or from a magnetic tape or other suitable device controlled by a computer (off-line).
The document description is previously transmitted and stored in the character generator disc memory 60. The document content is assumed to be a line by line format with control characters indicat;ng a selection of fonts, forms, and graphic addition. The content description is translated by the input 2~ element 10 from the host computer description to one that is understood by the character generator 12.
A character text to page image transformation by the three processors 62, 64 and 66 in the character generator 12 is then performed in the following sequence in accordance with the present invention.
Step 1. The document text is conveyed to the text RAM 96 and processed by the controll processor 620 In particular a page ~approximately 2000 characters) is extracted and listed in a character text list (CTL) in the text RAM 96. Each character in the CTL is described in four sixteen bit words containing the following information:
3S a. Controls - character code, font selection, scan offset from reference, and orientation.
b. X direction position of the character reference point.
c. Y direction position of the character reference point.
do font character starting word address in the font RAM 94.
llle character text list typically has 2K entries in the text RAM.
Pages of more than 2K characters are processed in 2K character segments.
There are at least two ways to process pages with more than 2K
characters. ~ one embodiment~ it is possible to pick a convenient se~ment of up to 2K random characters from the character text list (CTL). A complete run length coded field stream (RFS) overlay page ;s created into a serial parallel memory module 74 in the first pass. A second segment of 2K
characters is then processed and merged with the overlay from the Iirst pass into a new overlay. Thus, subsequent passes of 2K characters are merged with the overlay of the proceeding pass until all the characters of the page are processed and merged. This method requires as may 2K character passes as the number of 2K segments.
~ another embodiment, it is possible to presort the eomplete page by sorting it into vertical ~scan direction) strips of 2K character segments andstoring them onto the disc memory 60 or a memory module 74. ~uccessive strips are called in and processed in a continuous pass, starting from the left side of the page. This method takes only one long pass processing n by 2k characters. In general, the processing time is related to the number of characters on a page. It should be noted that the 2K threshhold is an arbitrary number. It should also be noted that only those fonts required by the CTL
need to be in the font RAM 94 when a page is processed in segments.
Step 2. The character text list (CTL) is next processed by the control processor 62 to extract those characters that are actively involved in the current scan and form an input scan line list (ISLL) in the scan RAM 92.
Assuming the scan is in the Y direction, the current scan is the ~th lîne acrossthe page~ Using a portrait page, the Y direction is along the long side, for example, Irom bottom to top and the X direction is along the short side9 for example, from left to right.
The first ISLL would eontain characters from the left verticle strip of the page for a certain number of sc~n lines ln the X direction. Each character in the ISLL is described by three 16 bit words as follows-l~ Currerlt forlt RFS starting word ~ddress. Note that the width of the character as well as the end o~ each scan line are denoted in the RFS itself(16 bits).
2. Y direction position of the ch~racter reference point (13 bits).
3. g direction position of the character refel~ence point at which the character should become acffvely processed. The character entries in the ISLL must be sorted by the control processor 62 in proper order. Namely, the characters to be processed by the æcan processor 64 for any line must be in ascending Y starting position order and new characters starting at later than the Xth line must be in ascending X starting positions of successive segments of adjacent characters. The ISLL is self-terminated by an entry in which the 5 font RFS address is all zeros.
Step 3. The ISLL is passed on by the control processor to the scan processor 64 for RFS generation. The scan processor keeps an alternating active scan line list (ASLL) in sean RAM 92. Each character in the active scan list (ASLL) is described by a double 16 bit word as follows:
1. Y starting position reference (13 bit) 2. Current font RFS starting word address (being updated for each Xth scan line) 16 Bits. Note that the width of the character as well as the end of each scan RFS, are denoted in the R~S content of the font.
The scan processor processes each char~cter entry from the 15 current ASLL and stores the updated entry of the same character in the alternative ASLL in succession. However, if the character font terminates (denoted by an end code 1111 folls)wed by a control code 0000), the entry is notstored thereby removing it from the ASLL.
Durin8~ the processing, the current X position is compared with the 20 ~ starting position of the next character of the ISLL to anticipate a new character starting in the next scan line. In that case, the ISLL character entryis stored into the ASLL. Thus, the alternate ASLL is updated with the proper character sequence for the next scan line. At the end of each scan line (terminated by an entry with the font RFS being all zeros), the alternate ASLL
25 and the current ASLL are exchanged.
RFS generation is a simple iteration process for each character entry in the ASLL done in the scan processor as follows 1. The current Y position is subtracted from the charaeter Y
starting position. If the result is negative, this character overlaps with the 30 last ~aracter. Ihe result normally is expected to be zero or positive. An appropriate number of zeros9 in RFS fields, is appended to the output RF~.
2. The font RFS of the character is then processed and appended to the output RFS one field at a time until an end code is detected. As this is done, the current Y position is advancedO
3O The font RFS address is updated be~ore storing the two word entry in the alternate ASLL.
4. The ne~ct e~try in the ASLL is accessed to repeat from Step l.
If the new entry access contains zeros as the font RFS address, the end of the ASLL is reached and an appropriate end code is appended, and the RFS
generation of the current scan line is complete.
When the RFS register has accumulated two 16 bit words of RFS, the two words are stored in the image RAM 98. These two words are stored using the current output RF5 address. Note that for a faster version9 the image RAM 98 could be structured as an FIFO store.
Step 4. The RFS in the image RAM 98 (or in the FIFO store) is passed on to the image processor 6fi for merging with any required overlay and for conversion into appropriate standard data compaction codes by the compressor 68. The final output is stored into its assigned buffer memory module 74. When a buffer memory module 74 is filled up, the control processor 62 is notified via a bufer memory program interruptO The control processor will then assign a new buffer memory module to the image processor. The control processor will also route the filled buffer memory module 74 to the next appropriate operation; namely, transmission to the printer 14, via the communication channel 16 for printing.
In accordance with the present invention, the merging process of two R~S's into one output RFS in a compressed form is done by the image processor 66. Starting from the beginning of the two RFS's, the current field OI one is compared with that of the other in the following manner:
Case 00/ll - Namely, both fields are denoting the same polarity:
The shorter field value with the appropriate polarity is passed onto the output RFS. 111e RFS having the shorter field value advances to the next field, with appropriate polarity updated. The other RFS is not advanced by its field value and decreased by the shorter field value. ~ case that the two field values are equal9 both RFS7s advance.
Case lO/Ol - Namely, the two fields are denoting opposite polarities:
The shorter field value is passed onto the output R~S with a 1 polarity. The RFS having the shorter field value adv~nces to the next field, with appropriate polarity updated. The other RFS is not advanced but its field value is decreased by the shorter field valueO
1~ case that the two field values are equal9 both RFS's advance.
Y~
The above Steps 1 to 4 repeat in this pipeline process;ng fashion for each 2K segment OI the page until the complete page i5 transformed and until the complete document is transformed.
With reference to Figure 8, there is shown an exemplary multiple 5 printing system in accordance with the present invention. A plurality of printers 14 are driven by a pair of disc memories 60. The disc memories 60 aPe connected to a plurality of character generators 12. Generation of characters onto the disc memories permits complete pages or page sets to be generated be~ore any printer is committed to reproduce the pages of text. It should be 10 noted that many other system configurations are possible but in partieular the character generators can be off line to convert the input character into raster scan format and can allocate the converted characters onto the disc for directly driving the printer or for retrieval and merging with current con-verted eharacters.
While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be appreciated that numerous changes and modifications are likely to occur to those skilled in the art, and it is intended in the appended claims to cover allthose changes and modifications falling within the true spirit and scope of the 20 present invention.
Claims (10)
1. In an apparatus for generating characters to be scanned in raster format from character input byte informa-tion, the combination of:
a character input device providing character input byte information, a disc memory, a character generator connected to the input device and the disc memory for converting the character input byte information into bit streams, and bit streams being allocated onto the disc memory, a buffer memory, a buffer memory bus, an output marker connected to the disc memory, the buffer memory including a plurality of buffer memory modules, the buffer memory bus including a plurality of buses, each of the memory modules being interconnected to one of the plurality of buses, the character generator including a processor memory and control processor, the control processor con-nected to the character input device for sorting the charac-ter input into scan line lists, a scan processor, the scan processor being connected to the control processor and trans-forming the scan line lists into run length coded field streams, and a merge processor interconnected to the buffer memory modules and the disc memory through the plurality of buses, the merge processor for forming overlays, the processor memory including a control memory, a scan memory, a font memory and a text memory, the scan memory and the font memory connected to the scan processor through a first processor memory bus, the control memory, the scan memory, and the text memory being interconnected through a second processor memory bus, the second processor memory bus being connected to the control processor and a third processor memory bus, the third processor memory bus interconnecting the control memory, the font memory, the text memory and the merge processor, the second processor memory bus being independent of the third processor memory bus whereby char-acter input byte information is converted into marker output format and stored in the disc memory for conveyance to the output marker.
a character input device providing character input byte information, a disc memory, a character generator connected to the input device and the disc memory for converting the character input byte information into bit streams, and bit streams being allocated onto the disc memory, a buffer memory, a buffer memory bus, an output marker connected to the disc memory, the buffer memory including a plurality of buffer memory modules, the buffer memory bus including a plurality of buses, each of the memory modules being interconnected to one of the plurality of buses, the character generator including a processor memory and control processor, the control processor con-nected to the character input device for sorting the charac-ter input into scan line lists, a scan processor, the scan processor being connected to the control processor and trans-forming the scan line lists into run length coded field streams, and a merge processor interconnected to the buffer memory modules and the disc memory through the plurality of buses, the merge processor for forming overlays, the processor memory including a control memory, a scan memory, a font memory and a text memory, the scan memory and the font memory connected to the scan processor through a first processor memory bus, the control memory, the scan memory, and the text memory being interconnected through a second processor memory bus, the second processor memory bus being connected to the control processor and a third processor memory bus, the third processor memory bus interconnecting the control memory, the font memory, the text memory and the merge processor, the second processor memory bus being independent of the third processor memory bus whereby char-acter input byte information is converted into marker output format and stored in the disc memory for conveyance to the output marker.
2. An apparatus for generating characters to be scanned in raster format from character input byte information including:
a character input device providing the input byte information, a first memory for storing character input byte information, a character generator communicating with the memory, a buffer memory, a buffer memory bus connected to the buffer memory and the memory storing the input byte information, and an output marker, the output marker connected to the character generator, the character generator including a control processor connected to the character input device for sorting the character input byte information and a scan processor interconnected to the buffer memory and the first memory through the memory bus, the control processor providing scan line lists from the byte information, the scan processor transforming the scan line lists into coded field strings, the coded field strings providing an output marker scanning format whereby character input byte informa-tion is converted into output marker scanning format and stored in the first memory for directly driving the output marker.
a character input device providing the input byte information, a first memory for storing character input byte information, a character generator communicating with the memory, a buffer memory, a buffer memory bus connected to the buffer memory and the memory storing the input byte information, and an output marker, the output marker connected to the character generator, the character generator including a control processor connected to the character input device for sorting the character input byte information and a scan processor interconnected to the buffer memory and the first memory through the memory bus, the control processor providing scan line lists from the byte information, the scan processor transforming the scan line lists into coded field strings, the coded field strings providing an output marker scanning format whereby character input byte informa-tion is converted into output marker scanning format and stored in the first memory for directly driving the output marker.
3. The apparatus of claim 2 wherein the buffer memory includes a plurality of buffer memory modules and the buffer memory bus includes a plurality of buses, each of the memory modules being interconnected to a memory bus.
4. The apparatus of claim 2 including a processor memory, the processor memory including a control memory, a scan memory, a font memory and a text memory, the scan memory and the font memory connected to the scan processor through a first processor memory bus, the control memory, the scan memory, and the text memory being interconnected through a second processor memory bus, the second processor memory bus being connected to the control processor and a third processor memory bus, the second memory bus being dependent of the third memory bus, the third memory bus interconnecting the control memory, the font memory, and the text memory.
5. The apparatus of claim 4 including a communication channel and a communication interface, the communication interface being interconnected to the buffer memory bus, the communication interface including communication receive logic and communication send logic.
6. The method of operating a character generator having a processor, the character generator driving an output marker in a printing system comprising the steps of:
(a) converting character coded input data into bit streams in the processor;
(b) allocating the converted bit streams into a memory;
(c) merging the retrieved bit streams with other currently converted bit streams in the processor;
(d) allocating the merged bit streams onto the memory; and (e) retrieving the converted bit streams from the memory to drive the output marker.
(a) converting character coded input data into bit streams in the processor;
(b) allocating the converted bit streams into a memory;
(c) merging the retrieved bit streams with other currently converted bit streams in the processor;
(d) allocating the merged bit streams onto the memory; and (e) retrieving the converted bit streams from the memory to drive the output marker.
7. The method of claim 6 including the step of retrieving the merged bit streams from the memory to drive the output marker.
8. The method of claim 6 including the step of leaving the merged bit streams in memory for later use.
9. The method of claim 6 wherein the step of merging the retrieved bit streams with other currently converted bit streams includes the step of compressing both bit streams into compressed format.
10. The method of claim 9 including the step of merging the retrieved and currently converted bit streams into compressed format whereby it is not necessary to first decompress the retrieved and currently converted bit streams before merging.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/270,949 US4493049A (en) | 1981-06-05 | 1981-06-05 | Shared resource clustered printing system |
| US270,949 | 1981-06-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186417A true CA1186417A (en) | 1985-04-30 |
Family
ID=23033530
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000404544A Expired CA1186417A (en) | 1981-06-05 | 1982-06-04 | Shared resource clustered printing system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4493049A (en) |
| EP (1) | EP0067004B1 (en) |
| JP (1) | JPS57203186A (en) |
| CA (1) | CA1186417A (en) |
| DE (1) | DE3279829D1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4591997A (en) * | 1983-11-28 | 1986-05-27 | Polaroid Corporation | Method of storing and printing image with non-reentrant basic disk operating system |
| DE3501194C2 (en) * | 1985-01-16 | 1997-06-19 | Bosch Gmbh Robert | Method and device for data exchange between microprocessors |
| JP2636866B2 (en) * | 1988-01-30 | 1997-07-30 | キヤノン株式会社 | Information processing method |
| US4918622A (en) * | 1988-11-16 | 1990-04-17 | Eastman Kodak Company | Electronic graphic arts screener |
| US4977458A (en) * | 1988-11-16 | 1990-12-11 | Eastman Kodak Company | Apparatus for addressing a font to suppress Moire patterns occurring thereby and a method for use therein |
| US4916545A (en) * | 1988-11-16 | 1990-04-10 | Eastman Kodak Company | Electronic graphic arts screener that suppresses Moire patterns using pseudo-random font selection |
| US5274473A (en) * | 1989-08-04 | 1993-12-28 | Intergraph Corporation | Rapid variable angle digital screening |
| DE4402134A1 (en) * | 1994-01-26 | 1995-07-27 | Microplex Elektronische Dokume | On line archiving system for printed data |
| US5729665A (en) * | 1995-01-18 | 1998-03-17 | Varis Corporation | Method of utilizing variable data fields with a page description language |
| US6243172B1 (en) * | 1995-01-18 | 2001-06-05 | Varis Corporation | Method and system for merging variable text and images into bitmaps defined by a page description language |
| US5791790A (en) * | 1996-03-13 | 1998-08-11 | Lexmark International, Inc. | Method and apparatus for providing print job buffering for a printer on a fast data path |
| US7302438B1 (en) | 1997-07-18 | 2007-11-27 | Tesseron Ltd. | Method and system for flowing data to an arbitrary path defined by a page description language |
| US6487568B1 (en) * | 1997-07-18 | 2002-11-26 | Tesseron, Ltd. | Method and system for flowing data to an arbitrary path defined by a page description language |
| US6049390A (en) * | 1997-11-05 | 2000-04-11 | Barco Graphics Nv | Compressed merging of raster images for high speed digital printing |
| US7315979B1 (en) | 1998-11-09 | 2008-01-01 | Tesseron Ltd. | Method and system for dynamic flowing data to an arbitrary path defined by a page description language |
| US7102773B1 (en) | 2000-07-19 | 2006-09-05 | Sharp Laboratories Of America, Inc. | Method for multicast of documents |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4070710A (en) * | 1976-01-19 | 1978-01-24 | Nugraphics, Inc. | Raster scan display apparatus for dynamically viewing image elements stored in a random access memory array |
| US4079458A (en) * | 1976-08-11 | 1978-03-14 | Xerox Corporation | High resolution character generator |
| US4149145A (en) * | 1977-02-17 | 1979-04-10 | Xerox Corporation | Fax processor |
| CA1100644A (en) * | 1977-06-30 | 1981-05-05 | James G. Belleson | Raster printer with sufficient printing flexibility |
| US4203154A (en) * | 1978-04-24 | 1980-05-13 | Xerox Corporation | Electronic image processing system |
| JPS5585983A (en) * | 1978-12-21 | 1980-06-28 | Nec Corp | Print control unit |
-
1981
- 1981-06-05 US US06/270,949 patent/US4493049A/en not_active Expired - Lifetime
-
1982
- 1982-05-25 DE DE8282302669T patent/DE3279829D1/en not_active Expired
- 1982-05-25 EP EP82302669A patent/EP0067004B1/en not_active Expired
- 1982-05-27 JP JP57090479A patent/JPS57203186A/en active Pending
- 1982-06-04 CA CA000404544A patent/CA1186417A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0067004A3 (en) | 1983-08-10 |
| EP0067004B1 (en) | 1989-07-19 |
| US4493049A (en) | 1985-01-08 |
| JPS57203186A (en) | 1982-12-13 |
| DE3279829D1 (en) | 1989-08-24 |
| EP0067004A2 (en) | 1982-12-15 |
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