baxter@zola.ICS.UCI.EDU (Ira Baxter) (05/29/90)
I recently flamed the entire PC world, including UNIX OS porters, for stupid interrupt system design; I now understand that the problem seems to be active drivers on each I/O board for each interrupt level. I want to at least apologize to the UNIX OS porters, for making the best of a bad thing. :-{{{ The flame to the idiot hardware designers... well, *that* still stands. And malarkey about how the PC wasn't designed for big systems is no d--- excuse (comments about how it wasn't designed at all, well, now, those make sense!). Given all that... has anybody made the ISC 2.0.2 X5 ASY update operate with more than one device on the same interrupt level? The docs explicitly say that some serial ports really do allow multiple devices on the same level. How can this possibly work? What do serial ports do differently on the bus to allow a logical or of interrupts? I have tried configuring in ths driver with a standard dual serial (COM1: and COM2: for MSDOS) with an internal modem (COM4:), hacking ASY_2_VECT to be level 3, but apparantly the output interrupts get mangled, and stuff comes out at the rate of 1 ch/second. Obviously... some weird interrupt conflict. IDB (714) 856-6693 ICS Dept/ UC Irvine, Irvine CA 92717
haugen@bulus3.BMA.COM (John M. Haugen) (05/29/90)
In article <9005282014.aa08953@PARIS.ICS.UCI.EDU>, baxter@zola.ICS.UCI.EDU (Ira Baxter) writes: . . . > Given all that... has anybody made the ISC 2.0.2 X5 ASY update operate > with more than one device on the same interrupt level? The docs > explicitly say that some serial ports really do allow multiple devices Yes IBM goofed in their first attempt at the bus (ISA) by not allowing shared interrupts. But there second attempt (Microchannel) does. Also I believe that the interrupts on the ISA bus are edge triggered. It would be hard to share interrupts that are edge triggered. Microchannel is level sensitive. That is the interrupt line is not dropped until the card driving the interrupt is referenced by reading or writing to it's I/O registers. That would make it much easier to share interrupts. > IDB > (714) 856-6693 ICS Dept/ UC Irvine, Irvine CA 92717 John M. Haugen Domain: haugen@bma.com Bull Micral of America UUCP: ...!uunet!bulus3!haugen 900 Long Lake Road ATT: 612-633-5660