Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!tut.cis.ohio-state.edu!ucbvax!RELAY.PROTEON.COM!acm From: acm@RELAY.PROTEON.COM Newsgroups: comp.protocols.tcp-ip.ibmpc Subject: Re: Interrupt vectors for PC Ethernet cards Message-ID: <8906191352.AA20323@monk.proteon.com> Date: 19 Jun 89 14:02:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: Proteon, Inc., Westborough, MA 01581 [(508)898-2800] Lines: 34 Organization: Ontario Ministry of the Environment Message-Id: <396@moegate.UUCP> Sender: pcip-request@twg.com -------------------------------------------------------------------------------- I've seen this discussed before. In fact I'm using this hack on one of my machines. It seems to work but I'm concerned that it may not be reliable. Can anyone who really understands how the PIC's work comment on the implications of strapping the hardware to IRQ2 and calling it IRQ9 in software? Also it doesn't do you any good on the DOS side of things if you're using a commercial package, none of them try to do this. This goes back to when the AT was introduced by IBM. What they did was expand the PIC to 2 PIC's. In order to do this you must use a cascade of the first to the second in hardware and in order to do this they took the int2 connection to do it. In order for software to work on int2 they then made int9 look like the old int2 of the PC. It is somewhat inefficient but it does work on most stuff. Thus on an AT or compatible the int9 is identical to int2. Automatic software discovery of the int connected will usually get int9 but it is really coded like int2 in software, ie the vector is at the location of int2. Hope this helps understand what is going on. You are NOT in any problem by using int9 in software with int2 in hardware (provided it works for you in your particular situation as it should with all compatibles.) BTW the changes are in the hardware bios and there is where the "fix" is done. -Alan Marshall, VP Proteon Inc. 2 Technology Drive CCMAIL: acm at proteonwebo Westboro, MA 01581-5008 ARPANET: acm@Proteon.com tel: (508)898-2120 MHS: acm @ ProteonW