CD-ROM too slow though dma is enabled?

factorx · n00b Joined: 05 Apr 2003 Posts: 8 Location: Hagen, Germany

Hi

I think my cdrom drive is much too slow (40x, ata-133 ide channel)...

kha · n00b Joined: 19 Mar 2003 Posts: 41

If I recall correctly 1x = 150kBps, wich brings your 40x to a max of 5.8MB/s.
But this is purely theorical, most 40x rarely go faster than 36x even by th end of a disk.
Further more it is quite frequent that the reading speed on the begining of the CD is half the maximum theorical value. So a reading at the begining of a CD should be for you around 20x (2.9MB/s).

The fact that you are a 2.36 can mean a lot of things, the mos probable being that your CD-Rom is actually a slow starter (some 40x can be as slow as 10x in the begining of a CD). But I sincerly doubt there is a configuration error. You might be able to tweak a little bit to gain some speed, but I don't think it is worth the pain.

Oh also, no CD-ROM drive on eatrh can achieve DMA or UDMA speeds even a 100x (And I sincerly hope nobody will ever be stupid enough to do one of those) would cap at 14MB/s. UDMA on CD-Rom is just here to tell you that you can use a 80 thread IDE cable with no problem and no slow downs on the rest of the channel.(Older CDROM can make the whole channel fall back to standard EIDE).

Kha
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