what is multi-word dma mode?

[Darkhawk28]

anybody know?

 

[John]

DMA Mode 1 11.1 MB/s 40-pin IDE 40-pin
Multi-word DMA Mode 1 13.3 MB/s 40-pin IDE 40-pin
Multi-word DMA Mode 2 16.6 MB/s 40-pin IDE 40-pin
Ultra ATA Mode 2 33.3 MB/s 40-pin IDE 40-pin
Ultra ATA Mode 4 66.6 MB/s 40-pin IDE 80-pin
Ultra ATA Mode 5 100 MB/s 40-pin IDE 80-pin

 

[Darkhawk28]

i have a 52x creative labs cd-rom... and windows xp has set it to mw dma mode 2 ... why?

 

[Pariah]

A word is 2 bytes (16bits). The original ATA DMA transfer modes were single word modes, which meant only one word of data was sent at a time. These were quickly replaced by mulitword DMA transfers which are exactly what they sound like, more than one word transferred at a time. All hard drives even remotely recent use multiword DMA transfers. It's not something you really need to worry about.

"mw dma mode 2 ... why?"

Fancy technical term for saying the drive can transfer data at a maximum of 16.7MB/s.

 

[tornadobox]

check your BIOS, i had to chage the setting of my Lite-On in my BIOS to DMA 2, and now it shows up as Ultra DMA Mode 2

 

[Rand]

<< i have a 52x creative labs cd-rom... and windows xp has set it to mw dma mode 2 ... why? >>



It's quite possibly the default for that drive. Many CDROM's default to multi word DMA mode 2. It's nothing to be concerned with, MW DMA2 offers more then double the maximum bandwidth that a 52X CDROM drive can use anyway.
One would need a theoretical 110X CDROM to even hit a peak 16.5MB/s transfer rate.

 

[Pariah]

In John's post, the number 80 should be followed by "wire" not pin. We know he knows that, looks like he fell asleep at the wheel.