UDMA question

NascarFool · Post by **NascarFool** » Fri Jan 19, 2001 11:20 am

System Specs:
Athlon 700 @ 950
300 watt Antec PS
Epox 7KXA mother board
384megsPC133 @ CAS 3 (3 @ 128megs)
13.6 gig WD ATA66 7200rpm (partitioned in half)
20 gig WD ATA 66/100 7200 rpm (partitioned in half)
OEM HP 1.44 floppy
Acer 50x IDE CD Rom
Yamaha 16x10x40x IDE CDRW
Realtek 8139A NIC
Voodoo5 5500 AGP
SB Live X-gamers

Win98SE

Question:
DMA is enable in the Bios and in Windows. On boot up the hard drives show as UDMA66, Acer CDRom as UDMA33 and the Yamaha as UDMA16. Shouldn't the Yamaha drive be at UDMA33?

Stryker · Post by **Stryker** » Sun Jan 21, 2001 8:10 pm

and the Yamaha as UDMA16

I take from the above that you mean UDMA66.

If you have 2 ide devices (one with UDMA66 & the other with UDMA33) on the same channel it will show the correct dma capability of each device at bootup though the device with UDMA66 will drop back to UDMA33 so as the mobo controller can communicate with both devices at one mode..

Me thinks that's what you wanted to know.

NascarFool · Post by **NascarFool** » Sun Jan 21, 2001 8:39 pm

OK, my mistake. The hard drives are on the Primary controller running at ATA66. The Acer CD Rom and the Yamaha 16x burner are on the Secondary Controller at DMA33 and DMA 16 respectively. Shouldn't the Yamaha be DMA33 also ?

Splitfire · Post by **Splitfire** » Sun Jan 21, 2001 9:08 pm

*sigh...*

...though the device with UDMA66 will drop back to UDMA33 so as the mobo controller can communicate with both devices at one mode.

FALSE! WRONG! INCORRECT! This is one of the most propagated lies about IDE out there. This is no longer true, nor has it been since around the HX chipset (or so, maybe TX or LX). Its called 'independent device timing,' and it has been included in every chipset since the aforementioned time frame. For whatever reason, Intel did not make a big deal out of this so very few people know it. Since then you can put devices of multiple speeds on the same channel and they will both operate at the highest speed possible (be it limited by the controller or the device). I'm not holding anything against you Stryker, its just a common mistake.

Stryker · Post by **Stryker** » Mon Jan 22, 2001 12:15 am

Splitfire,

No problemo bro

, that was my bad and indeed a mistake on my part.

Thanks for the heads up!

Darkheart · Post by **Darkheart** » Mon Jan 22, 2001 4:47 am

Just in case anyone is wondering the chronoglogical order of those motherboards to date is:

VX (a lot of you will have had your pentiums running on these), One of the big noises at the time is that both these boards would be PCI 2.1 complaint. Introduction of UDMA on some later versions of this board.
|
-->Released simultaneously although VX went into production and distributioin a little more quickly.
|
HX (Could cache more than 64Mb)

TX (Couldn't cache 64Mb but had Independant Device Timing for IDE as well as much hyped support for UDMA).

FX (ill fated Pentium Pro boards).

LX (First run of P2 motherboards (233-333 66Mhz FSB)

EX (Low end LX, never really flew)

KX & GX (More attempts to get Pentium Pro working properly)

NX (First Xeon board, marking end of Pentium pro debacle)

BX (Second run of P2 Motherboards, still in common use because of Intel taking AGES to get the I815 out and working) .

Darkheart