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Inst. 2 CD rom drives in the same IDE computer.

longarm asked
Medium Priority
Last Modified: 2010-04-27
I am attempting,(with no luck), to Install a primary cd rom to do my software work on and a 2nd cd changer for playing music on while I work. The primary is a 100x that uses a buffer of 600mb and the changer is a 4x8x. The problem is that if I start the cd changer 1st the 100x works fine. if I start the 100x 1st the changer trys to draw from the buffer and freezes the whole system. I have already tried resetting up the cdroms on different jumper settings and the only way it will come close to working is to set the 100x on 2nd master and the changer to 2nd slave. I don't know how to seperate to drives by using different IRQ settings so if that is the answer please be specific on all the steps in this process.
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By trying this, it now has knocked out my modem(us rob.56k video). The modem will be recognized and clicks as if it is going to initialize but gives me an error that there is no dial tone. I attempted to reinstall it and it works until rebooted and then it is back to not working again. Diagnostics shows no conflict nor does the system device mngr.

From "Control Panels", remove the definition for your modem.
Also, remove the associated COM port.
Shutdown & reboot, and let Windows "detect" it.
Then, click on "modem" and "properties",
and see which COM port and IRQ have been selected,
and tell us.


I tried your advise and it locked up the computer to the point I had to start from ground 0.I formatted the hdd,wrote 0's to all of it then partioned it. reinstalled win 95 2.5 and reinstalled all of the perif's. The modem set it self on com3 and the IRQ list on startup only lists pnp or legacy isa. If there is another break down of the list, I don't know where to look for it.

Ground zero? Ouch! That was very unexpected. Thanks, Bill Gates.
So, what's your current status?
How are the hard-drives and CD-ROMs connected to the IDE channels?
Is your modem working?
What do you mean by "IRQ list on startup" ?
Is this something which your BIOS displays,
when you cold-boot your computer?
In "Control Panels", when you select the modem,
and click on "properties", what is displayed?


The current status is still the same the modem clicks at initiat. but will not dial. The hdd(jump mstr) and the 100x cdrom(slave) are on IDE #1. The cd changer(jump mstr)is on IDE #2.
The IRQ list that I know of is on the CMOS set up on start up when you push delete when prompted to.
Control Panel (modem)displays:"General"port:USR56k video modem(com3). Max. speed 115200bps. "Conection" data bits=8,parity=none
stopbits=1. x=wait for dialtone before dialing. x=cancel if not connected in 60sec.
"Port settings"=default
"Advanced settings"x=use error control,x=compress data,x=use flow control*hardware rts/cts. Modulation=standard.
x=check mark on item......

Another IRQ list can be obtained by running the 'MSD' program,
from a DOS prompt.  Seeing the output could be helpful.

If you use a COM1 mouse it is not very good to connect your modem to COM3 (ie. change a jumper to push the modem to use COM4, refer to your modem manual for the jumper setting) It depends on your telefon provider if on the line is dialtone (eg. in my country the ONLY ONE telefon provider is BTK, and my line has no dialtone, so I have removed the check on 'Wait for dialtone before dialing').
It is a bad idea to use 100x CD-ROM with it's ugly dumb 600M cache-file [the CD-ROM actual speed is 24x and the newest CD-ROMs are 40x, the 600M cache speed-up some appz, but not all, some are slowed down, make 600M diskspace useless, and never reach the speed of 100x - 100x150KB=15MB/s (that is only the theoretical maximum, in real world a 40x 'standart' CD-ROM will be faster in all applications, and the newest technology with multiply lasers make the newest 40x 'true' CD-ROMs MUCH MUCH faster).

Offer: 1)Better disable the cache option - then your 24x(real) and the Changer could work better together
         2)Sold your 100x CD and buy a 40x

Do you really have 600MB of cache?
Given a cost of about $1 per MB for "normal" RAM,
this must be a very-expensive unit,
and I wonder why "second" suggests that you sell it?

However, 'second' could be correct about COM1/COM3 conflicts.
I use COM4/IRQ3 for my modem, and it works,
because my COM2/IRQ3 is never used for anything.

I suggests that longarm sell it's 100x CD becouse for deliver it's full potential it need 650MB cache on the HDD, to image the CDs. However one of the newest 40x CD-ROMs will be faster than the longarm's CD-ROM even with 650MB cache. And a 40x offer very little (if any) incompatibly, problems with other hardware, etc. (so the problem with the 2 CD-ROMs can disapeer - "the changer trys to draw from the buffer and freezes" - the changer try to read from the cache of the 100x and that cause the system to hang) So if for longarm is hard to sell the 100x and buy another "standart" CD-ROM, he must use the 1) offer:  "Better disable the cache option - then your 24x(real) and the Changer could work better together"
Longarm, try it (and the COM/IRQ setting-change too) and tell us what happen.
best wishes!
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