J
Joel Ramirez
I'm having trouble understanding DMA. Is there
a tutorial available somewhere?
TIA.
a tutorial available somewhere?
TIA.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
J
Jan
Joel Ramirez said:I'm having trouble understanding DMA. Is there
a tutorial available somewhere?
TIA.
How about Googling for Ultra DMA?
Jan
D
Duddits
link may wrapI'm having trouble understanding DMA. Is there
a tutorial available somewhere?
TIA.
http://whatis.techtarget.com/definition/0,,sid9_gci213903,00.html
regards
Dud
--
What did the fish say when he hit a concrete wall?
Dam!
C
CBFalconer
Joel said:I'm having trouble understanding DMA. Is there
a tutorial available somewhere?
DMA stands for Direct Memory Access. It is very simple. When a
peripheral wants to transfer data (say a single byte) it simply
steals a memory cycle, and writes or reads that just as the CPU
would. This avoids interrupting the CPU and forcing it to perform
an i/o cycle for each item. Instead the system interrupts the COU
only when the complete transfer (of some number of bytes) is
complete, and now present in a known memory buffer.
The details vary with systems. IBM clones tend to have built in
DMA controllers, which do all the bus controlling. Other systems
may simply accept a DMA request, and when that is acknowledged the
bus lines are free for something else to control.