Browse Prior Art Database

Controller Architecture for Advanced Function Dot Matrix Printer

IP.com Disclosure Number: IPCOM000038999D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Harwood, FC: AUTHOR [+5]

Abstract

Advanced function printers accept high level vector graphics commands as well as character codes and bit images. Such printers typically print vectors by emulating graphics displays, which requires a full size bit map of the page, or by emulating pen plotters, which requires both forward and reverse forms movement. The present printer controller architecture embodiment utilizes a task handling concept which provides complete freedom of image generation for both text and graphics without either of these requirements. The figure shows that the printer controller microcode is divided into three parts: the Attachment, the Dot Generator, and the Mechanism Controller.

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Controller Architecture for Advanced Function Dot Matrix Printer

Advanced function printers accept high level vector graphics commands as well as character codes and bit images. Such printers typically print vectors by emulating graphics displays, which requires a full size bit map of the page, or by emulating pen plotters, which requires both forward and reverse forms movement. The present printer controller architecture embodiment utilizes a task handling concept which provides complete freedom of image generation for both text and graphics without either of these requirements. The figure shows that the printer controller microcode is divided into three parts: the Attachment, the Dot Generator, and the Mechanism Controller. The central Dot Generator communicates with the attachment through the Task Interface and with the Mechanism Controller through the DIT Interface (DIT = Dot Image Table). Both interfaces are RAM areas. The Attachment handles the host communication protocol, receives and decodes the printer input data stream from the host (which may be in any one of the various printer code sets) and generates print tasks which are temporarily stored in a buffer area in the Task Interface, to await input to the Dot Generator. The resultant task stream is essenti ally a generic data stream within which each task is a high level description of a print object such as a line of text, a vector, an encoded bar code, etc. A text task contains the sequence of code points to be printed, font ID, color, location on the page, etc. A vector task consists of the coordinates of its end points, color, thickness, line type, etc. A bar code task consists of the bar code type, sequence of code points whose bar code is to be printed, location on the page, etc. The Attachment also keeps track of the presentation position of text characters. This requires information as to the size of the character font currently being decoded. Since font tables containing this information are kept in the Dot Generator, and a new font table is requested by the Attachment each time a font change is detected, it is seen that at any given time the Attachment contains only the current font table. The Dot Generator processes Print Tasks...