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Printer Character Generator With Image Feature

IP.com Disclosure Number: IPCOM000034404D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Fedak, JF: AUTHOR [+2]

Abstract

Fig. 1 shows a data flow for the character generator (C-Gen). This C-Gen takes data via the channel through a Printer Channel Adapter (PCA). The processor interrupts the print data from the channel. The image to be printed can be either characters or graphic pictorial image. In either case this image must be placed in the pattern store for characters (PSC). When the dot patterns, one for black, zeroes for white, are sent to the printer, they are formatted in quads (4 by 4 patterns of bits) and stored in the PSC. All patterns to be printed must reside in the PSC. The data that tells the printer where to print the patterns is interrupted by the processor. The processor builds a table of codes, which the sequencer will interrupt as the page is being printed, to move the patterns from PSC to the raster buffer (RB).

This text was extracted from a PDF file.
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This is the abbreviated version, containing approximately 53% of the total text.

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Printer Character Generator With Image Feature

Fig. 1 shows a data flow for the character generator (C-Gen). This C-Gen takes data via the channel through a Printer Channel Adapter (PCA). The processor interrupts the print data from the channel. The image to be printed can be either characters or graphic pictorial image. In either case this image must be placed in the pattern store for characters (PSC). When the dot patterns, one for black, zeroes for white, are sent to the printer, they are formatted in quads (4 by 4 patterns of bits) and stored in the PSC. All patterns to be printed must reside in the PSC. The data that tells the printer where to print the patterns is interrupted by the processor. The processor builds a table of codes, which the sequencer will interrupt as the page is being printed, to move the patterns from PSC to the raster buffer (RB). The sequencer is controlled by a microprocessor, present design of which is a Motorola 68000. It determines if there is room in the RB to place the patterns, and moves the patterns from the PS to the RB if there is room. The RB is a rotating buffer which holds the print patterns for one-half inch of the print page. The RB is loaded by the sequencer and then the print head control (PHC) starts taking data out of the RB and passing it to the print head as the print head requires. As the PHC clears part of the RB the raster buffer control (RBC) informs the sequencer that the RB has more area for patterns. The sequencer fills the RB from the PCS by interrupting the codes the processor placed in a table in the writable control store (WCS). The sequencer fetches the codes by the direct memory access (DMA) bus.

(Image Omitted)

If large sections of a picture are sent to the printer, the printing has to stop while the processor or sequencer format the data and store it in the PSC. There are two bottle necks that slow down this process. (1) The processor/WCS data handling; and (2) the PSC is in full time use when the printing process is taking place, which leaves only the space between pages to format and store picture images into the PSC. Fig. 2 data flow for the C-Gen with image feature shows a data flow that eliminates both of these probl...