On Fri, 15 Dec 2000, Pat Wendorf wrote:

> - The SCSI performance seems a little slow.  I know this is a fairly old
> machine, but I have a few x86 boxes of similar CPU speed (33mhz), and
> the IDE on my 486's seems significantly faster in NetBSD.  Not that I'm
> complaining, I'm just wondering if it's the drive or the architecture. 
> Once something is loaded into memory, it seems to run reasonably fast.

Paul Goyette <paul@whooppee.com> Answers:
>Architectural limitation.  Mac's don't have DMA, so we have to simulate
>it.  It is _very_ slow.

Not fully true.

The right answer is:

Only some Macintosh have DMA implentemented, so we have...

Example of Apple Computer that implement DMA:

Macintosh IIfx (yes old);
Apple II with Apple SCSI High Speed Card (same age) *.

Emile


* I have a SCSI demo disk that let people see a part of Star Wars (yes, a piece
of the movie) using full Apple IIGS Screen (geyscale) with a perfect image run
flow: around 30 seconds taken from the chase in the meteorite field. This was
done back in 1990 (I think).