15 Nov
2007
15 Nov
'07
4:36 a.m.
On Tuesday 13 November 2007 22:17, dwight elvey wrote:
> From: rtellason at verizon.net> > This is
where I get a little puzzled
> sometimes. Like that BB2 I mentioned, > that uses DMA to send a string of
> bytes to the disk controller chip rather > than using the processor to do
> those transfers. Why is not immediately > apparent to me since the
> processor isn't doing anything else at that point > anyhow...>
Why does your quoting not handle line breaks well?
Hi
I once wrote code to take avantage of DMA to disk. I was doing a search
that required a case insensitive search. I found that on the processor
I was running, it took almost as much time to read a track as it
did to search the data on the track. I'd only have to wait, doing
nothing on the first read. After that, I would just have to wait a
little while until the next track was read, because I'd started
the second DMA before I started searching the first buffer.
That makes sense.
In a multi user system, one could be handling all
kinds of
activities while the buffer was being loaded.
Multi-user in an 8-bit context doesn't sound real terrific to me, for some
reason, though I don't see a problem with multiprocessing if it's done
right.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin