Audio CD and hard drive

[flyboy747]

I have a computer that has an Aopen 56x cd-rom and a Plextor CDRW. Whenever I play an audio cd in the Aopen, the hard drive led blinks simultaneously with the cd-rom access light. When I play the same cd in the Plextor, the hd led doesn't blink. It does this both with and without the audio cable on the Aopen. Any ideas what could be blinking when using the Aopen? I guess it's not a serious problem, but I was just curious. Thanks.

[AlienDyne]

It's not actually the HDD led. It's the IDE led and since the CD-ROM and the HDD share the same IDE channel, the led flashes when activity is detected by one IDE device.

[confus-ed]

AlienDyne is right(per usual), if you had another led attatched to the second channel(newer/ upmarket cases have these,I use the sleep LED or add one) you'd see that light up when your plextror came on, its just indicating activity on that ide channel not necessarily the hard disk.

You infer that this only happens with audio cd's all I can say is that certain read methods can't use dma(streaming audio?), so you'd get more activity on the controller to the cpu and thus see it more.

[flyboy747]

[quote]Originally posted by AlienDyne:
<strong>It's not actually the HDD led. It's the IDE led and since the CD-ROM and the HDD share the same IDE channel, the led flashes when activity is detected by one IDE device.</strong><hr></blockquote>

In this case, the hard drive is the only drive on primary ide by itself and both cdroms are on the secondary chain. Are you saying that the led flashes for both ide channels? If you are, I've never seen another computer that does that.

[Asterchild]

I was under the impression that the HDD led blinked with activity from any device on either/both IDE channels. I've never seen a motherboard that supported two HDD led's for the primary and secondary channels respectively.

Confus-ed: "...if you had another led attatched to the second channel(newer/ upmarket cases have these,I use the sleep LED or add one) you'd see that light up when your plextror came on, its just indicating activity on that ide channel not necessarily the hard disk."

So motherboards actually give two connections for IDE activity? I don't recall ever seeing two.

Ö
Aster

[flyboy747]

I was actually under the impression that it only lit up when there was activity on the primary ide. My main computer (the one I'm on now) only lights up when there's hard drive activity (which the hd is the only drive on the primary chain).

On the computer this post is about, if the case were true with the led coming on on every access on either chain, wouldn't the led blink as well when the Plextor was reading (Plextor and Aopen cdroms are both on secondary ide)?

Like I said before, this isn't causing any problems, I would just really like to know why it's doing this. Thanks for any comments or suggestions!

[Asterchild]

Now that I think about it and sorta mess around with my PC, the HDD led only blinks when my HDD's on my primary channel are working. I have my CDRW on the secondary and I put in a CD, but the LED did not blink until the HDD started working in response to the CD.

I guess I never really thought about it before, I just assumed it worked on both channels. But it makes sense that the LED would only work with the primary channel. Sort of a duh on my part.

Ö
Aster

[flyboy747]

After looking a little closer, I have noticed that the hdd led does seem to blink with the Aopen cdrom when it reads not only audio cds but also data cds. So I guess it is what ya'll were talking about about it working with the secondary ide chain too. BUT, it only does it on the Aopen...the led doesn't blink when reading data or audio cds off of the Plextor. I guess maybe it just shows activity for the master (Aopen) and not the slave (Plextor). I don't know, but I thank ya'll for your help and appreciate everything.

**UPDATE**

After switching the Plextor to the secondary master, the led still blinks with the Aopen. I'm just giving up on this because I'm positive now it has something to do with the way the Aopen reads the CDs. Thanks again for your help.

[confus-ed]

I have before me a Soltec 75Drv, which has on its complex header(the bit where you add the reset switech etc) which has two two pin connectors labeled 1st HDD Led and 2nd HDD Led. So now you know for sure Asterchild.

All I can say is that whatever way you look at it, reading a cd results in some data being transfered to the HD, even if its only the directory reading being cached, so the LED will flash. Now if your CDRW has a big fat cache, then it won't do it as much, disable the supplementary cache in windows for the cd and you will see less unexpected HDD activity, only slower...

[Asterchild]

Thanks for the info confus-ed. Always learning something new around here.

Ö
Aster