Which DMA Channel is an IDE Harddisk assigned to

Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
Post Reply
raywill
Posts: 3
Joined: Thu Nov 23, 2006 9:48 am
Location: China
Contact:
Contact raywill

Which DMA Channel is an IDE Harddisk assigned to

Post by raywill »

DMA Channel 2 is assigned to floppy Disk .
Which DMA Channel is an IDE Harddisk assigned to?

Can anyone give a short description how an harddisk driver does a DMA read/write ?

Thanks in advance!
Enjoy Life~
Top
User avatar
Brendan
Member
Member
Posts: 8561
Joined: Sat Jan 15, 2005 12:00 am
Location: At his keyboard!
Contact:
Contact Brendan

Re: Which DMA Channel is an IDE Harddisk assigned to

Post by Brendan »

Hi,
raywill wrote:DMA Channel 2 is assigned to floppy Disk .
Which DMA Channel is an IDE Harddisk assigned to?
The short answer is none, unless you've got an old XT. For more recent computers PIO is faster so they stopped using the ISA DMA. Since then they've added "PCI IDE accelerators", which is basically bus mastering PCI for hard disk transfers (which makes things a little messy considering the IDE/ATA controller is an ISA device for backward compatability purposes).
raywill wrote:Can anyone give a short description how an harddisk driver does a DMA read/write ?
IIRC it was "chipset specific", but Intel release a specification for bus mastering that most modern chipsets follow. According to this web page the specification is a de-facto standard called "Programming Interface for Bus Master IDE Controller Revision 1.0".


Cheers,

Brendan
For all things; perfection is, and will always remain, impossible to achieve in practice. However; by striving for perfection we create things that are as perfect as practically possible. Let the pursuit of perfection be our guide.
Top
Post Reply

Return to “OS Development”