U
Unknown
Let's drop it. You don't answer my questions.
Bob I said:
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B
Bob I
I did answer your question repeatedly, but you simply refuse to accept
the fact that DMA has no bearing whatsoever on the how much of a
quantity of installed RAM is available.
the fact that DMA has no bearing whatsoever on the how much of a
quantity of installed RAM is available.
D
dennis
Bob said:DMA is a data transfer method, it doesn't USE memory. A 32 bit operating
system can communicate directly with 4GB address locations. The hardware
is addressed starting at the top of the listing, while memory (RAM) is
addressed starting at the bottom. When the 2 lists meet, that is the
limit of usable RAM. Lets say you put in the full 4 GB of memory sticks.
And lets say the two list meet at 3.1 GB. That is your usable memory.
Add more hardware, say a second video card, the top list extends down
further and now they meet at 2.7 GB. Take that new card back out and it
moves back up to 3.1 GB. Remove the other high-end video card and
replace it with some low end unit, now you have 3.5GB of usable memory.
DMA has very much to do with RAM. I think you might have DMA and MMIO
mixed up.
B
Bob I
dennis said:DMA has very much to do with RAM. I think you might have DMA and MMIO
mixed up.
Nope,
http://en.wikipedia.org/wiki/Direct_memory_access
D
dennis
Bob said:
I am not sure I am understanding you correctly. DMA is not the same as
MMIO, if that is your claim.
B
Bob I
dennis said:I am not sure I am understanding you correctly. DMA is not the same as
MMIO, if that is your claim.
No what I am saying is that DMA has absolutely no bearing on where the
split in the 4 GB address space occurs between usable memory and
hardware. It is due to the items and type of hardware you have
installed, RAM ends up with the address space that isn't occupied by
hardware(provided you have installed enough RAM to use all the addresses).
U
Unknown
Interpreting your responses, one is left with the idea that the RAM input
area of a DMA device is
also available for a program. That is not the case. That is the point I try
to make.
Some people even consider a program running if it is in RAM. That also is
not the case.
area of a DMA device is
also available for a program. That is not the case. That is the point I try
to make.
Some people even consider a program running if it is in RAM. That also is
not the case.
B
Bob I
I'm beginning to think there is a language translation problem.
I fail to understand how you can believe I am implying that hardware
addresses can be used for RAM or user memory. Especially when I keep
repeating that it is NOT available to be used!!!!
DMA is what is used to transfer information from a Hardware address to a
memory address. And DMA is not used for all hardware devices. If you
want to call the hardware address a DMA device then it is a mis-use of
the term. And it is still the hardware assigned to the addresses that
precludes them from being used for RAM.
A program must be loaded into memory before the CPU may process the
instructions it contains. This also is immaterial to where the line of
demarcation exists between usable memory and hardware addresses.
I fail to understand how you can believe I am implying that hardware
addresses can be used for RAM or user memory. Especially when I keep
repeating that it is NOT available to be used!!!!
DMA is what is used to transfer information from a Hardware address to a
memory address. And DMA is not used for all hardware devices. If you
want to call the hardware address a DMA device then it is a mis-use of
the term. And it is still the hardware assigned to the addresses that
precludes them from being used for RAM.
A program must be loaded into memory before the CPU may process the
instructions it contains. This also is immaterial to where the line of
demarcation exists between usable memory and hardware addresses.
U
Unknown
Yep! Definitely a language problem.
Bob I said:I'm beginning to think there is a language translation problem.
I fail to understand how you can believe I am implying that hardware
addresses can be used for RAM or user memory. Especially when I keep
repeating that it is NOT available to be used!!!!
DMA is what is used to transfer information from a Hardware address to a
memory address. And DMA is not used for all hardware devices. If you want
to call the hardware address a DMA device then it is a mis-use of the
term. And it is still the hardware assigned to the addresses that
precludes them from being used for RAM.
A program must be loaded into memory before the CPU may process the
instructions it contains. This also is immaterial to where the line of
demarcation exists between usable memory and hardware addresses.
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