By Utsav-Goswami

most of us using optical drives and hard drives sometime or the other have to bear the

problem of the transfer mode being changed from UDMA to pio.It is very irritating because

the cpu usage shoots up to almost 100% and no multi tasking is possible.

So have no fear because UTSAV is here.

I will give a step by step tutorial to change the transfer mode to UDMA from pio without

reinstalling windows.

There are also some registry hacks so use them at your own risk.

to open registry editor goto start then click on run and type in ‘regedit’ except the

quotes. press enter.

For optimum transfer efficiency, the IDE channels should be using UDMA (Ultra Direct Memory

Access) and not PIO Mode (Programmed Input/Output). But Windows frequently decides on many

systems to use the latter.

So what’s the diff between the major transfer mode groupings? It’s most importantly about

what hardware in your system is providing the grunt for data transfers:
Mode
Explanation

PIO
Programmed Input / Output

The CPU manages the transfer of data between system memory and the storage device. Supports

bus speeds up to 16MB/sec, if your processor can keep up. Nothing built this century should

be using PIO.

DMA
Direct Memory Access

The bus-mastering system controller (a.k.a. DMA controller) is programmed to manage the

transfer, freeing the CPU to do other stuff while the DMA controller does its thing. It’ll

also support bus speeds up to about 16MB/sec.

UDMA
Ultra Direct Memory Access

A modern (I think 64-bit?) version of the DMA method. It’s the current standard for high

speed storage devices with bus speeds up to 100MB/sec.
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