Browse Prior Art Database

Line Buffer Queue

IP.com Disclosure Number: IPCOM000045663D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Booth, JR: AUTHOR

Abstract

Typical low-cost trail printers receive a data stream which describes the characters to be printed in a left to right manner. To permit of bidirectional printing, a line buffer is conventionally employed to hold the data until an end of line character is received. At this time the line length may be computed and a direction of print decision may be made. The line buffer usually located at a fixed location includes (random-access memory (RAM) of sufficient size to accommodate the expected data stream without overflowing. This method of RAM allocation leads to a condition where the entire line buffer RAM allocation is rarely used, which means that this expensive resource is not fully utilized. In some printers, multiple line buffers, like the one described, are employed which compounds the RAM utilization problem.

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Line Buffer Queue

Typical low-cost trail printers receive a data stream which describes the characters to be printed in a left to right manner. To permit of bidirectional printing, a line buffer is conventionally employed to hold the data until an end of line character is received. At this time the line length may be computed and a direction of print decision may be made. The line buffer usually located at a fixed location includes (random-access memory (RAM) of sufficient size to accommodate the expected data stream without overflowing. This method of RAM allocation leads to a condition where the entire line buffer RAM allocation is rarely used, which means that this expensive resource is not fully utilized. In some printers, multiple line buffers, like the one described, are employed which compounds the RAM utilization problem. Disclosed is a method by which RAM may be used more effectively in multiple line buffer trail printers.

A particular line buffer structure is illustrated in the drawing. Each line buffer 10, in the illustrated instance line buffer A, is made up of a fixed length header portion 11 or line buf fer control block and a variable length data field 12. The header can contain descriptive information, such as the leftmost and rightmost character locations, the post index distance and the pitch to be used, but must contain a ready flag and a count of the bytes in the data field 12. The ready flag is employed to signal when a line buffer is ready t...