Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!dali.cs.montana.edu!milton!yoda.eecs.wsu.edu!wbonner From: wbonner@eecs.wsu.edu (Wim Bonner) Newsgroups: comp.os.os2.programmer Subject: Re: COM3, COM4 support Keywords: COM3 Message-ID: <1991Mar09.202258.24347@eecs.wsu.edu> Date: 9 Mar 91 20:22:58 GMT References: Reply-To: wbonner@yoda.UUCP (Wim Bonner) Organization: Washington State University, Pullman Lines: 19 In article gah@hood.hood.caltech.edu (Glen Herrmannsfeldt) writes: >The documentation for DevHlp SetIRQ seems to require vector 9 for IRQ2, >and it is supposed to be redirected. Well, the IRQ2 bus line goes to >interrupt line 9. This may not work for some other reason, I only >tested it once. I am writing this while logged in on COM3. Actually the way I understand it, you should never try to use interrupt 2 directly. The second interrupt controller in an AT is cascaded off this interrupt from the main controller. If you try to use IRQ2, you are in effect trying to use the same interrupt as any device trying to use irq8-irq15. This includes your hard drive controller if your machine is standard in its use of interrupts. Wim. -- | wbonner@yoda.eecs.wsu.edu | | 27313853@wsuvm1.csc.wsu.edu | | 72561.3135@CompuServe.com |