Re: Antwort: Re: Antwort: Re: Antwort: Re: Macintosh IIvx (Performa 600)

[Michael Schmitz <schmitz@schmitzm.hip.berkeley.edu>]

On Tue, May 25, 1999 at 01:39:32PM +0200, guido.dampf@syseca.de wrote:
> Yes, of course, but the messages telling me, that everything is o.k. The
> system is just awfull slow.

So? It's a Mac ... get used to it. Apple took the worst possible design
decision in not using DMA for SCSI data transfer. The kernel has to get each
and every byte from the SCSI controller and write it to its destination (and
on top of that, the kernel has to handshake the whole SCSI protocol in
software because the SCSI chip in the old Macs is a real braindead piece of
silicon). 
On the upside: it was relatively easy to write the SCSI driver - with DMA,
and Apple not telling anything, you wouldn't even have Linux on your Mac
now.

	Michael