On Mon, 6 Oct 1997 01:09:09 +0100 Jorge Ferreira writes: >Hello > > >... >Herbert Graf wrote: >> >> -----Original Message----- >> From: Sean Breheny >> To: PICLIST@MITVMA.MIT.EDU >> Date: Sunday, October 05, 1997 14:55 >... >> I just though about this, I also have one free, IRQ 7, not the >best IRQ >> to use, probably why it is free in almost every machine I use! :) >> >... > >In fact it isn't free, the IRQ7 is dedicated to the printer port. >Althought MS-DOS makes no use of it, it is used by other operating >systems that use interrupt driven spoolers for their printing jobs. As >you see it might be a very bad idea to use IRQ7 as your software can >get >confused if you send something to the printer. Unfortunately, the various printer and card manufacturers didn't standardize exactly how the printer IRQ should work. As a result, practically no software uses it, instead using a timer interrupt to poll the printer. The printer card should have a jumper on it to connect the IRQ, just remove the jumper and there should be no bad effect to using IRQ7 for something else.