burton@parcvax.Xerox.COM (Philip M. Burton) (12/11/86)
I would like to configure a second parallel port in my PC AT as LPT3, and use the LPT2 interrupt for another purpose. DOS doesn't recognize LPT3 without a mono card installed. It seems silly to get a mono display card, which I don't need, just to get LPT3 support from DOS. Does anyone know of a patch to DOS, preferably 3.1, to support a normal LPT1 plus LPT3? (Do I lose any significant functionality, driving either an Epson or a Diablo 630 printer?) Alternatively, does anyone know how to hack a cheapie AT parallel/serial, or AT multifunction card to make the parallel port look like the one in the mono display card? Please be very specific. Thanks in advance, Phil Burton Xerox Corp
johnl@ima.UUCP (John R. Levine) (12/15/86)
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?