Enabling DMA and Memory Issue

[Brangwen]

My Esteemed Colleagues:

Does enabling DMA on ones HD increase the memory draw? I was using voice recognition software (Dragon Naturally Speaking) to dictate a few letters into WordPerfect. My internet software was open but minimized, and I believe that's all I had open. In any event, after finishing the second 2-page letter, I received a message that read "Dragon Software Out of Memory." I was then just barely able to save my work then had to reboot. I'm using a P3 600MHz cpu (oc'd to 720MHz) with 128 MB PC100 SDRAM, Win98se, 20 GB Maxtor (7200 rpm ATA66) HD. I enabled the DMA on the Maxtor after reading a tip somewhere that this was a way to increase HD performance. Is my memory "problem" in any way related to the DMA being enabled?

Thx!

Brangwen http://sysopt.earthweb.com/forum/wink.gif

[Erap!]

Hmmmm... i have the exact same hard disk as you. I have DMA enabled but so far, i have no problems running out of memory. If it help, i run an A7V with an 800 t-bird w/ 128mb ram

[spark25]

What is your virtual memory set at? Bump it a notch and next time that low memory pop -up appears hit control/alt/delete and see what is in the background and stop unnecessary software.
Yes,if properly configured you will see an increase in performance from your hard drive using Direct Memory Access (DMA).
Your memory problem is not caused by DMA.
128MB should be enough to run what you were running.
If you kill unnessary programs and fix your swap file that should drive away the pop up low memory screen.

[Brangwen]

I appreciate the responses. I have my virtual memory set at minimum 131 MB, maximum 131 MB.

Think that should be increased?

Thx! Brangwen http://sysopt.earthweb.com/forum/wink.gif

[Erap!]

YESSSSSSSSSSSSSSSSSSSSSSSSSSSS!!!!!!!!!!!!!!!!!!!! !!!!!!!!!

[Beemers]

I only have 32 megs here and I run a conservative 300 & 300.

You might want to check and see if your DMA is actually doing anything.
It seems that when using this method (as opposed to buying a system which had DMA (properly) enabled by the OEM), an entry of the registry is not updated. To check, Open the file Mshdc.inf (found in \Windows\Inf), and look for the header [ESDI_AddReg], it should look like:

[ESDI_AddReg]
HKR,,DriverDesc,,"ESDI Port Driver"
HKR,,DevLoader,,*IOS
HKR,,PortDriver,,ESDI_506.pdr
HKR,,IDEDMADrive0,3,01
HKR,,IDEDMADrive1,3,01

If the two bold-faced lines shown above appear (with the other 3 lines), you are set. If not, add the 2 (bold) lines, and manually remove all IDE devices from Device Manager (Control Panel > System, Device Manager tab), the system will tell you to re-boot, and it will re-detect the controller, and set them up in DMA mode.

Cheers!

[djurom]

DMA is only a way to increase performance of your HDD. When HDD uses DMA, it's not using your memory to increase transfer rate but CPU cycles.

In normal mode HDD has to wait every time for CPU to process the data it has in one or more cycles. CPU to decrease time interrupts reserves a few cycles for himself. Enabling DMA HDD "steals" that cycles to process his data or he shares one cycle with CPU.

When DMA is disabled HDD uses memory (RAM) to load his data reserved for CPU and when CPU says he's free data is unloaded from RAM. With DMA enabled HDD first inspects does he have any free cycles and then using interface controller (IDE, which has to support DMA,) sends directly to CPU which decreases time of transfer. With more time he can send more data than normal PIO mode.