Pitch Selection of a Parallel-Attached Printer to a Personal Computer
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
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.