Staggered burning speeds on T40 CDRW/DVD?

[kkapoor]

I have a Thinkpad T40 with a 16X CDRW/DVD on it. I have burned quite a few cd's on it in the 7 months that I have owned it. One thing that I have noted is that whenever I am burning a cd the speed of the burner seems to follow a pattern:

For example when I am burning an entire 700MB CD the process goes as follows:

1. 1st 3 Mins - burns at 8X
2. Next 2 Mins - burns at 12X
3 Last minute - burns at 16X

I seem to get average burn speed of about 10X at all times. Seems like it is underperforming to me, but I could be mistaken. Is this normal?

[xtypestereotype]

Thats normal
It relates to the "physics" of spinning and the way cds are designed...
New cd drives run at CAV, or constant angular velocity
Which means they simply spin at a constant speed
The consequence of this is that you will get smaller data transfer rates from the inner parts of the cd and greater from the outer parts...
Older CD drives used to spin at variable speeds...
They would spin faster when the lenses were positioned in the inner parts of the media and then slow down as the lenses moved towards the outer parts... This slowing down would result in a constant amount of KBps... This still applies to music CDs...
Music CDs run at a constant 150KBps, which means music CD players have to "slowly" slow down the spining as the tracks go by

[kkapoor]

Thanks so much for that bit of technical knowledge. It's always a pleasure to learn more.

[xtypestereotype]

No probs
Its good to refresh my mind on those things anyway...