als@bohra.cpg.oz (Anthony Shipman) (06/01/90)
This is a reply to thank the people who helped and to report what I have learned: /-- | Is IRQ2 usable with SCO Unix? \-- wul@sco.com (Wu Liu -- Member, Technical Staff The Santa Cruz Operation, Inc.) replied: > Yes. The standard configuration for network cards used internally > with TCP/IP (3c501s, 3c503s, WD8003s) is IRQ2. > > I haven't tried setting a tape controller to use IRQ2; all of the tape > drives I've configured have been set for IRQ5, or in one case, IRQ7. > I'll have to give this a try sometime... It turns out I had a hardware problem. The vital clue was: > From: gemini@geminix.mbx.sub.org (Uwe Doering) > > 386/ix works with IRQ2, too. The only difficulty may be that you have to > remember that on AT and 386 boards IQR2 on the bus side corresponds to > IRQ9 on the software side. Therefor if you want to use a device on IRQ2 > you have to tell UNIX (during the device installation) that it is on > IRQ9. If the configuration program won't let you do this you can change > it by hand in the /etc/conf/sdevice.d directory. > > There is one thing to consider, though. Most EGA and VGA cards use IRQ2 > for their vertical retrace interrupt. This interrupt is absolutely > unnecessary under UNIX, and I don't know any DOS programs that need this > IRQ, either. It's there simply for compatibility reasons with the original > IBM EGA card. You have to disable this IRQ on these cards. Some have a > jumper for that purpose, but on most you have to cut the track that leads > to the B4 bus contact (it's the fourth contact on the solder side, counted > from the side where the monitor connector is). I have done this several > times and havn't had any problems from that. > Cutting the IRQ2 line (edge connector B4) solved the problem. Both the tape controller and 3com ethernet board now work fine at IRQ2. I have settled on the ethernet board at IRQ2=9 and the tape controller at IRQ5 to give the ethernet board a higher priority. I don't know how important this is but it sounds good (and it's the standard SCO configuration). /-- | How can I use IRQ3 or IRQ4? \-- Again a hardware problem. The motherboard still had the serial ports connected to IRQ3,4. I haven't tried it but I expect that all I had to do was disable the serial ports in both software and hardware. -- Anthony Shipman ACSnet: als@bohra.cpg.oz.au Computer Power Group 9th Flr, 616 St. Kilda Rd., St. Kilda, Melbourne, Australia D