IRQ sharing , Intrnal Modem & CDRom Drive problem

  Ashar 11:42 23 Oct 2005

Dear Friends

My system runs on Window Me
and I have a trouble with my internal
modem & CD Rom drive

*I see following IRQ assigned to
devices at startup.
Display Controller IRQ 11
IDE Controller IRQ 14
Serial Bus Controller IRQ 9
SMBus controller NA
Multimedia Device 5
Simple COMM controller 5

Please notice that simple comm controller
and multimedia device share the same IRQ. Is this okay?

Problem with modem:

I frequently get disconnected while online
& sys hangs.
I have to reboot to start working again and next time it
assigns following IRQ
Display Controller - 9 IDE Controller 14
Serial Bus Contrlr 5 SMBus NA
Multimedia Device 11 Unknown PCI device 11

Sys now fails to detect modem & it detects modem as PCI
device or EarlyVGA device. I don't see entry for Modem in
Device Manager. I see Other device with yellow mark.
I removed this entry, uninstalled driver from Add/Remove
and then reinstalled modem using New Hardware
Wizard. But it didn't work. I have to reinstall modem almost

I sometimes see double entry for modem as follow:
HSP56Micromodem and HSP56MicroModem#2

Modem Resorces as shown in Device Manager:
Interrupt request 05
I/O range C000-C03F
Use Automatic setting is checked
Modem Hardware version 002

com port 3

DOS Support :
COM port COM3
Base Address 3E8
Interrupt 4

(please note here it shows interrupt 4 instead of 5)
It says modem is configured correctly . But advice to
free this resource if wish to use modem with DOS application
as IRQ4 is used by another device.

Control Panel>Modem shows no modem
installed for com1 & com2
It shows HSP56Micromodem for COM3

*problem with CDRom

Sys reboots when I load CDRom drive with
CD.It happens with almost every CDs
Sys restarts followed by scandisc & if I don't remove
CD , it will shut down automatically. I have to wait
for few minutes before I can restart my PC

CD Rom drive is samsung sc-152c
Settings: Target ID, logical unit Number - 0
Firmware Version CS04
Disconnect & Auto insert Notification are selected
Syn Data transfer Not selected
Removable & Int 13 unit grayed out
Current Drive letter assignment G
Reserved Drive letter (strat & end) None

Driver:It says driver provider Microsoft. It also
says no driver file is required or have been loaded for this device.

Please notee that I see same IRQ setting 5 for Multimedia device & Simple
Comm Controller at startup. Can this be the main cause for my
problem with CDRom & Modem?

I thank you all for kind support
Best Regards
Ashar Bhavesh


Please note:
DeviceManager shows no conflict for modem or CD Rom

  ashdav 12:03 23 Oct 2005

try putting the modem card into a different PCI slot and set IRQ in the BIOS to auto.

  woodchip 15:27 23 Oct 2005

If you had a conflict, it would not work at all. you need to check your line

  ashdav 16:47 24 Oct 2005

line faults wouldn't cause the CDrom to malfunction or IRQ conflicts,

  DieSse 17:22 24 Oct 2005

The modem is a siftware modem, and contains it's own COM port - that's why it installs itself as Com3, rather than on the Com1 or Com2 which alraedy exist in your system. In itself it's excatly what to expect, and not a problem.

If you don't use the computers serial ports, you can disable them in the BIOS and it will free up the IRQs that they use - this may be helpful on older systems.

ashdavs advice about a different slot, setting the IRQ detection to Auto, - and also set the OS Plug and Play to Enabled, is an excellent thing to try.

  Batch 18:16 24 Oct 2005

PCI was designed for devices to share IRQ, however sometimes devices don't work well together and moving one of the cards to another PCI slot enables a different IRQ to be used / shared with another device and can solve conflicts.

  woodchip 18:45 24 Oct 2005

Yes but you can only do that with a PCI modem. not a CNR or a AMR these have very short slot about 2" long

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