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New IRQs only an issue for ISA peripherals.
--
Peter
Shill For Hire
New Umm could you expand on that?
What does PCI, AGP substitute for the er eternal Interrupt? ESP?

(I think I understand 'interrupts' - the PDP-8 was described in first sentence as, an interrupt-driven minicomputer... so what am I missing?)

(Ignorant guess: PnP / Windoze makes their own up, outta hype + saved glitches from deceased tasks - stored in an .idx file (#237) for later usage. Each one has to be Registered, of course, so that no OS-interrupts may be used, or ones from an unRegistered second machine :-)
New Brother, can you spare an IRQ?
I think he means that PCI cards use a different method of assigning IRQs than ISA cards. It depends on the BIOS really and the motherboard hardware. Some IRQs are assigned to certain slots, it seems, and if you move the card you can change the IRQ it uses.
"I can see if I want anything done right around here, I'll have to do it myself!"Moe Howard
New PCI's designed to share IRQs. BUT...
like most PC hardware, there are exceptions.

Here's a good page with info on IRQ sharing on the PCI bus, with an emphasis on problems NICs can have.

[link|http://personal.bellsouth.net/sdf/h/b/hburgiss/dsl/survival/irq.htm| [link|http://personal.bellsouth.net/sdf/h/b/hburgiss/dsl/survival/irq.htm|http://personal.bel...ival/irq.htm]]

Basically, IIRC, the PCI bus is more sophisticated than the old ISA bus in that it can discrimiate between two devices raising the same interrupt signal. Edge- versus level-triggering seems to raise a flag with me. Check Google for more details...

HTH.

Cheers,
Scott.
New Good crib sheet..
Thanks. Saved.

Interesting re SBLive stealing an Irq for DOS use - about which Windoze is oblivious!

Also noted my E-machine has modem in 1st PCI slot adjacent to AGP! but - works like charm.

Good reminder too, to make sure I remembered to disable the secondary IDE and second floppy in BIOS in the new boxes.

Now as to edge VS level- triggering (??) - fer us scope types that rings a bell, but also a bit sophisticated for a toy box I'd a thunk: that is, for it to reliably discriminate / flip - for one trigger-level setting VS a slightly different criterion. At a 100 - 200 MHz bus rate, say !

(If you find that ref, be curious how they Do that.)


Thanx,

A.
New Edge versus Level triggering of interrupts...
I misrememberd. ISA uses edge, PCI uses level.

[link|http://mailman.real-time.com/pipermail/linux-kernel/2001-March/023682.html|Here's] a bit I found about it. I'm no expert on this stuff. There should be better info out there - especially on Intel's site.

HTH.

Cheers,
Scott.
New See what you mean. Heh! an analog! e- problem..
If my reading between lines is close enough:

What he's calling "edge" triggering is.. that sort of detector, commonly using a Schmitt Trigger circuit: a feedback device which enhances the risetime via.. yup pos feedback! to give a thus faster dV/dt as a trigger pulse. What he calls "level triggering" implies an intentionally 'slower" device which is not concerned with dV/dt so much as just "change state when V= x.yz V".

Guess I'll poke around a bit; hard to see how same line from an "Irq detector" under s/w control - could parse the two - but it seems that the Vectra didn't.. too well. How'd ya find That!?

(It's amazing the amount of stuff you can see with a real analog GHz scope on these boards - let alone decipher)


A.
New IRQ Sharing In Action
Here's my IRQ layout, as reported by Windows 2000:

IRQ Number\tDevice
9\tMicrosoft ACPI-Compliant System
11\tNVIDIA RIVA TNT2/TNT2 Pro
11\tIntel 82371AB/EB PCI to USB Universal Host Controller
11\tVortex Multifunction PCI Parent
11\tAureal Vortex 8830 Audio (WDM)
11\t3Com EtherLink XL PCI TPC NIC (3C900B-TPC) #2
11\tMass Storage Controller
15\tSecondary IDE Channel
8\tSystem CMOS/real time clock
13\tNumeric data processor
6\tStandard floppy disk controller
4\tCommunications Port (COM1)
3\tCommunications Port (COM2)
1\tStandard 101/102-Key or Microsoft Natural PS/2 Keyboard

Note all that stuff going through IRQ 11.
I'll also free up another IRQ when I gets me a PS/2 -> USB adapter for this here IBM keyboard.
--
Peter
Shill For Hire
New Re: IRQ Sharing is a two edged sword.
It's nice that a number of devices can share an interrupt - you can have more devices.

It's bad because when an interrupt occurs, you don't know who (i.e. which device) caused it or why. On an interrupt, additional interrupts are automatically disabled - interrupt handlers aren't themselves interrupted. The interrupt handlers of the associated device drivers for an IRQ are started one at a time, probably in the same sequence each time, and interrogate the associated device to see if it was the one that caused the interrupt. If not, the next device's interrupt handler is started. If so, the event is recorded, the interrupt condition in that device is reset, the next operation if any may be started, and interrupts re-enabled. If other devices had a pending interrupt the interrupt handling process (as above) would start again. Otherwise, whatever process was originally interrupted would resume.

The disadvantages of sharing interrupts are that 1) it takes longer to figure out what caused an interrupt and 2) that some devices, in effect, get preferential treatment. For good performance, it's important to arrange the sequence of device drivers so that the most frequently interrupting devices are serviced earlier.

Alex
New Amiga also shared IRQs
The IRQ number was related to the priority of the interrupt. I recall that the serial port operated on 2 IRQs - the higher priority IRQ was for receiving, the lower one for sending.

Darrell Spice, Jr.

[link|http://home.houston.rr.com/spiceware/|SpiceWare] - We don't do Windows, it's too much of a chore

New B*llsh*t.
Theory says they can and should share; practice says they could have and don't.
qts
New Some devices do not work well with others
like Modems for example, whenever I get a modem that shares an IRQ with another device, I get lockups in the Microsoft Dial-up networking, Procomm Plus, Hyper Terminal, etc.

They don't call it "Plug and Pray" for nothing. Almost enough to make you want to go out a buy a Macintosh and run OSX. :)
"I can see if I want anything done right around here, I'll have to do it myself!"Moe Howard
New Why...________________________________"almost"____??
New Why almost?
Well let's see some reasons why:

#1 Macintosh hardware usually costs more than the PC systems I can build by my hand.

#2 Macintosh hardware does not have as long a warranty as PC hardware. 1 Year verses 3 (sometimes 5) Years in most cases.

#3 Low end Mac hardware, such as the iMac, are not that easy to upgrade. Try getting a new motherboard and CPU for a $1299 iMac, verses the $799 generic ATX PC cased system. How about upgrading the video, audio, and adding a few more drives to an iMac verses the ATX system? Here comes the money! :)

#4 Virtual PC emulators are fine if you only have a few programs to run under it, but if you have over a dozen you might as well have a PC system run it.

#5 I've been burned by Apple and Apple tech support in the past. Just dealing with a different devil than Microsoft. :)

#6 I'd rather reformat and use Linux or OpenBSD instead, that way I don't need to change out all my hardware.

#7 I usually find a way around "Plug and Pray" by changing settings to "Manual" in the BIOS setup and changing the IRQs that each slot can use in the CMOS setup.

Of course these are just my reasons. I almost bought a grape 266Mhz iMac, but the guy almost wanted the "New" price for it despite it being a few years old already. At first he wanted $400, but kept raising the price. So I told him to forget it. Maybe one day, when I find one affordable, I'll have one to mess around with. I still have an old Macintosh SE and IIcx to use, I almost donated them to a church. They share a keyboard and mouse, ADB of course. I have a Mac to VGA adapter that I use with the IIcx. :)
"I can see if I want anything done right around here, I'll have to do it myself!"Moe Howard
New OK though not compelling for a non-techno wanting stability.
New You want stability for a non-techno?
Get a Nintendo 64, its cheaper and the games are better. Plus you can turn it off during a game and not foul up the OS. While you cannot do your taxes on it, or surf the web, for the gamers it will work fine.

But yeah, I can see the case for Macs and OSX to a non-techno who doesn't know any better.
"I can see if I want anything done right around here, I'll have to do it myself!"Moe Howard
     Presario 7110US, 17", color printer. $1499.97 Deal? - (Another Scott) - (21)
         Sounds good. -NT - (static)
         Wondering re Compaq - (Ashton) - (1)
             My mom's Presario 5000 seems pretty standard. - (Another Scott)
         Careful... - (bepatient) - (16)
             IRQs only an issue for ISA peripherals. -NT - (pwhysall) - (15)
                 Umm could you expand on that? - (Ashton) - (8)
                     Brother, can you spare an IRQ? - (orion)
                     PCI's designed to share IRQs. BUT... - (Another Scott) - (3)
                         Good crib sheet.. - (Ashton) - (2)
                             Edge versus Level triggering of interrupts... - (Another Scott) - (1)
                                 See what you mean. Heh! an analog! e- problem.. - (Ashton)
                     IRQ Sharing In Action - (pwhysall) - (2)
                         Re: IRQ Sharing is a two edged sword. - (a6l6e6x)
                         Amiga also shared IRQs - (SpiceWare)
                 B*llsh*t. - (qstephens) - (5)
                     Some devices do not work well with others - (orion) - (4)
                         Why...________________________________"almost"____?? -NT - (Ashton) - (3)
                             Why almost? - (orion) - (2)
                                 OK though not compelling for a non-techno wanting stability. -NT - (Ashton) - (1)
                                     You want stability for a non-techno? - (orion)
         Keyboard should be fine - (SpiceWare)

An eye is upon you... staring straight down and keenly through!
101 ms