DMA...

My teacher in school is teaching that DMA is no longer in use because it
is too slow...
Then how come that hard disk is faster in DMA than in PIO mode?

SysCold wrote:
>
> My teacher in school is teaching that DMA is no longer in use
> because it is too slow...
> Then how come that hard disk is faster in DMA than in PIO mode?

Your teacher, to put it gently, is full of it. Sounds like a
class where you want to remember just enough to spit it back at
exam time, and then rapidly forget it. Correcting the teacher is
unlikely to lead to good marks.

--
Chuck F () ()
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net> USE worldnet address!

On Sat, 31 Jan 2004 16:45:57 +0100, SysCold <> wrote:

>My teacher in school is teaching that DMA is no longer in use because it
>is too slow...
>Then how come that hard disk is faster in DMA than in PIO mode?

Did that teacher specify that PIO was the faster alternative (which of
course is untrue)?

It might've been simply that "DMA" was being considered in a vague
sort of way, as single or multi-word, not ultra DMA.

Always take what a lower-level course instructors say with a grain of
salt... an unfortunate side-effect of Windows is that it makes *some*
people feel more competent than they really are... even in areas not
so directly related to windows.

Here's a site to get a little more basic info:
http://www.storagereview.com/guide20.../modesDMA.html

"SysCold" <> wrote in message
news:bvgiie$qnq$...
> My teacher in school is teaching that DMA is no longer in use because it
> is too slow...
> Then how come that hard disk is faster in DMA than in PIO mode?

Perhaps your teacher was referring to UDMA as being a faster form of DMA??
PIO is certainly not faster than either DMA or UDMA (U stands for Ultra). I
believe WindowsXP will automatically select what is best for most drives.

Comcast News wrote:
> "SysCold" <> wrote in message
> news:bvgiie$qnq$...
>> My teacher in school is teaching that DMA is no longer in use
>> because it is too slow...
>> Then how come that hard disk is faster in DMA than in PIO mode?
>
> Perhaps your teacher was referring to UDMA as being a faster form of
> DMA?? PIO is certainly not faster than either DMA or UDMA (U stands
> for Ultra). I believe WindowsXP will automatically select what is
> best for most drives.

Usually it does, although I've found that with some optical drives it
defaults to 'PIO mode only'. I change that to 'DMA if available' and usually
get UDMA mode 2 and a lot faster throughput times.
--
~misfit~

~misfit~ wrote:
> Comcast News wrote:
>> "SysCold" <> wrote in message
>> news:bvgiie$qnq$...
>>> My teacher in school is teaching that DMA is no longer in use
>>> because it is too slow...
>>> Then how come that hard disk is faster in DMA than in PIO mode?
>>
>> Perhaps your teacher was referring to UDMA as being a faster form of
>> DMA?? PIO is certainly not faster than either DMA or UDMA (U stands
>> for Ultra). I believe WindowsXP will automatically select what is
>> best for most drives.
>
> Usually it does, although I've found that with some optical drives it
> defaults to 'PIO mode only'. I change that to 'DMA if available' and
> usually get UDMA mode 2 and a lot faster throughput times.

Just to confirm what I said above, I put a new PC together yesterday and XP
Pro had the CD-RW as UDMA mode 2 and the CD-ROM as PIO only. I changed it in
device manager/IDE/peoperties and now the CD-ROM is running UDMA mode 2.
--
~misfit~