Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!mit-eddie!genrad!decvax!ima!johnl From: johnl@ima.UUCP (John R. Levine) Newsgroups: comp.sys.ibm.pc Subject: Re: LPT3 support without an installed Mono Display Card - Query Message-ID: <295@ima.UUCP> Date: Sun, 14-Dec-86 20:44:01 EST Article-I.D.: ima.295 Posted: Sun Dec 14 20:44:01 1986 Date-Received: Tue, 16-Dec-86 22:48:47 EST References: <133@parcvax.Xerox.COM> Reply-To: johnl@ima.UUCP (John R. Levine) Distribution: na Organization: Javelin Software Corporation Lines: 16 Keywords: LPT3, DOS patch Summary: DOS doesn't use interrupts for lpt In article <133@parcvax.Xerox.COM> burton@parcvax.Xerox.COM (Philip M. Burton) writes: >I would like to configure a second parallel port in my PC AT as LPT3, and use >the LPT2 interrupt for another purpose. ... There's no need. DOS doesn't run the printer with interrupts anyway. The worst that can happen is that occasionally your interrupt routine will get called because of a printer interrupt rather than because of your device. Due to the poor design of the IBM printer interface, you can't run the printer with interrupts -- there's no way to keep from losing the interrupts. Programs that appear to do so such as the "print" print spooler are actually polling the printer when the clock interrupts. -- John R. Levine, Javelin Software Corp., Cambridge MA +1 617 494 1400 { ihnp4 | decvax | cbosgd | harvard | yale }!ima!johnl, Levine@YALE.EDU Where is Richard Nixon now that we need him?