Browse Prior Art Database

Pitch Selection of a Parallel-Attached Printer to a Personal Computer

IP.com Disclosure Number: IPCOM000040204D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Lederer, JF: AUTHOR [+2]

Abstract

A parallel-attached printer responds to a query command from a Personal Computer (PC) to indicate to the PC the pitch of a printer having different fonts or wheels of different pitches plugged therein. An EPROM, which contains software allowing a printer to recognize a new class of commands (referred to as query commands), is added to a parallel-attached printer. When a printer receives a query command from the PC, it responds through lowering its Select line, one of the parallel interface lines between the printer and the PC, to 0 volts if its pitch is that to which the query command is referring. If the printer is not in that pitch, it does nothing so that the Select line remains high.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 82% of the total text.

Page 1 of 1

Pitch Selection of a Parallel-Attached Printer to a Personal Computer

A parallel-attached printer responds to a query command from a Personal Computer (PC) to indicate to the PC the pitch of a printer having different fonts or wheels of different pitches plugged therein. An EPROM, which contains software allowing a printer to recognize a new class of commands (referred to as query commands), is added to a parallel-attached printer. When a printer receives a query command from the PC, it responds through lowering its Select line, one of the parallel interface lines between the printer and the PC, to 0 volts if its pitch is that to which the query command is referring. If the printer is not in that pitch, it does nothing so that the Select line remains high. To properly interpret each response from the printer, the PC must know that the printer is not processing other commands when a query command is sent. Thus, the printer is first sent a DeSelect command, which is to put the Select line down. The PC program waits as long as necessary for the printer to lower its Select line in response to the DeSelect command. When the printer lowers its Select line, the PC program knows that the printer is caught up with all commands sent to it prior to the DeSelect command. The PC sends the printer a Select command to raise the voltage on the Select line. Then, the query command is transmitted, and the Select line goes to 0 volts if it is in the pitch to which the query command...