MIT provides MULTICS source and documentation (DPS-8 simulation)
Roy J. Tellason
rtellason at verizon.net
Wed Nov 14 22:36:47 CST 2007
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?
> 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
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