Please explain differnce between Ultra DMA 0, 1, 2

[nealh]

I recently installed the miniport driver from AMD...version 3.14

my cdrom and cdrw have the option of running in various modes...both are UDMA 2 ....

There is PIO mode 4...which is 16mg/sec...vs UDMA which is ATA33...but does this really matter for cdrom/cdrw...

DMA ..has something called multiword DMA 0, 1, 2
UDMA...0, 1 ,2 ...what is the difference and is there really any practical performance differences??


Thanks

 

[AndyHui]

Please read the FAQ: Hard drive interfaces and standards

 

[nealh]

AndyHUi..I looked at the link...thanks...

but I still do not understand wha t the difference between UDMA 0, 1, 2...how that effects speed , performance and reliability..etc

I realize the PIO mode 4 is 16.6 mg/sec and UDMA is faster ..I guess more reliable???

 

[AndyHui]

UDMA2 = ATA33 = 33MB/s
UDMA4 = ATA66 = 66MB/s
UDMA5 = ATA100 = 100MB/s

The higher UDMA modes result in faster transfers, or faster performance.

PIO these days is generally a fallback for devices that cannot handle UDMA.

 

[nealh]

Thanks..so what does UDMA 0 and 1 mean???

 

[BruinEd03]

<< Thanks..so what does UDMA 0 and 1 mean??? >>



They're slower than ATA33...UDMA1 = slower (I think around 15MB/sec?) ...UDMA0 = slowest (I think around 8 MB/sec?).

-Ed

 

[rbV5]

Single word DMA 0, 2.1 MB/sec
PIO mode 0, 3.3 MB/sec
Single word DMA 1, multiword DMA 0, 4.2 MB/sec
PIO mode 1, 5.2 MB/sec
PIO mode 2, single word DMA 2, 8.3 MB/sec
PIO mode 3, 11.1 MB/sec
Multiword DMA 1, 13.3 MB/sec
PIO mode 4, multiword DMA 2, 16.6 MB/sec
Multiword DMA 3, 33.3 MB/sec
Multiword DMA 4, 66.6 MB/sec
Multiword DMA 5, 99.9 MB/sec
Multiword DMA 6, 133.3 MB/sec

 

[RoughDood]

and oh yeah you might want to include on those dma's and what not that it's zero to 33/mbs or zero to 66/mbs and so on it doesn't run at 66mb/s it runs upto that on a lot of them it means the they can go upto that amount
hoped that helped too

 

[nealh]

Very interesting...so udma is up to 33mg/sec..but multiword dma is up to 133/sec

So for a cdrw anything over 8mg/sec should have no impact on performance ...right??

 

[nealh]

BruinED03...under the VIA IDE tool with miniport 3.14 drivers it lists UDMA 0, 1, 2 all as ATA 33