DMA transfer code.

This is where you post all your requests for demos, intros, pubtros etc...

Moderators: Mug UK, lotek_style, Moderator Team

User avatar
SoLo2
Captain Atari
Captain Atari
Posts: 207
Joined: Wed Feb 04, 2004 4:09 am
Location: Spain
Contact:

DMA transfer code.

Postby SoLo2 » Wed Mar 17, 2004 8:55 pm

Hello!

I wish to use DMA to transfer
Memory 2 Memory.

I have tried modifying some
sources I found, but didn't
work.

I am searching for some
assembler to this respect.

Thanks,
SoLo2
~~~~~~~~~~~~~~~~~~~~~~~~~~*~~~
The BITS Club http://bits.atari.org

User avatar
SoLo2
Captain Atari
Captain Atari
Posts: 207
Joined: Wed Feb 04, 2004 4:09 am
Location: Spain
Contact:

Postby SoLo2 » Fri Mar 19, 2004 2:09 pm

Here is a little explanation as some
persons didn't seem to understand
the purpose of DMA memory2memory.

DMA is a chip that has some memory
in it. 32 Bytes does it have.
Normally, in the Atari ST, it copies
memory from main RAM into itself (buffering)
and out to Hard Disk or Floppy Disk.
And the other way round: from HD, FD
into its buffer and out to main memory.
All this with a little cooperation from the
68000 processor.
I wish to use its buffer capabilities to
copy from RAM into DMA chip, and then
from DMA chip back to RAM. Without
sending to FD or HD. This way I could
spare processor time, while memory
is being shifted.

thanks,
SoLo2
~~~~~~~~~~~~~~~~~~~~~~~~~~*~~~
The BITS Club http://bits.atari.org

User avatar
tobe
Atari God
Atari God
Posts: 1459
Joined: Sat Jan 24, 2004 10:06 am
Location: Lyon, France
Contact:

Postby tobe » Fri Mar 19, 2004 3:52 pm

Hi Solo2,

Did you have any hardware registers documentation about this ?
Will the 68k be usable while the dma being used ?
Are you sure dma is a chip, not a bus ?

On STE, you can use blitter to copy memory, it use dma, but it locks the 68K, i'am wrong ?

Mmm, that's a lot of questions :D !
step 1: introduce bug, step 2: fix bug, step 3: goto step 1.

User avatar
GT Turbo
Captain Atari
Captain Atari
Posts: 335
Joined: Tue Feb 17, 2004 9:41 am
Location: Alsace, France
Contact:

Postby GT Turbo » Fri Mar 19, 2004 3:54 pm

tobe wrote:Hi Solo2,

Did you have any hardware registers documentation about this ?
Will the 68k be usable while the dma being used ?
Are you sure dma is a chip, not a bus ?

On STE, you can use blitter to copy memory, it use dma, but it locks the 68K, i'am wrong ?

Mmm, that's a lot of questions :D !


You have raison Tobe, but you can split the bus for dma and 68000 work together, that must be the bit 6 of fffff8a3c.w, register of the blitter !!!


GT Turbo (Blitter bomber !!) :oops:
Never forget : Power is in your minds !!!

http://Cerebral-Vortex.net

http://Jagware.org

Gunstick
Captain Atari
Captain Atari
Posts: 258
Joined: Thu Jun 20, 2002 6:49 pm
Location: Luxembourg
Contact:

Re: DMA transfer code.

Postby Gunstick » Sun Apr 04, 2004 9:49 pm

SoLo2 wrote:Hello!

I wish to use DMA to transfer
Memory 2 Memory.



I don't think copying 32 bytes with the dma chip is worthwhile the pain.
The DMA chip steals cylces from the CPU, so I doubt it will even be faster.

And if you imagine that the parallax distorter is done like that because the scrolltext talks about using the DMA to shift the graphics, well that's a BIG joke :-)

Georges


Social Media

     

Return to “Demos - Requests”

Who is online

Users browsing this forum: No registered users and 1 guest