Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!lll-winken!lll-tis!ames!nrl-cmf!ukma!cwjcc!hal!nic.MR.NET!xanth!hoptoad!dasys1!alexis
From: alexis@dasys1.UUCP (Alexis Rosen)
Newsgroups: comp.sys.next
Subject: Re: Disk transfer speed (was Re: Some Answers, straight from NeXT)
Message-ID: <7255@dasys1.UUCP>
Date: 28 Oct 88 04:13:36 GMT
Article-I.D.: dasys1.7255
References: <938@ccnysci.UUCP> <8810250344.AA02429@esplanade.csri.toronto.edu>
Reply-To: alexis@dasys1.UUCP (Alexis Rosen)
Lines: 31

In article <8810250344.AA02429@esplanade.csri.toronto.edu> tjhorton@ai.toronto.edu writes:
>alexis@ccnysci.UUCP (Alexis Rosen) writes:
>>The Optical drive is a true read-write drive...
>>The SCSI controller is a next-generation (no kidding...) chip which support
>>4.8 MBYTES/sec. (can you say mainframe channel speeds?)  Of course, I don't
>>think you can get a SCSI drive which transfers this fast, but that will
>>change...
>
>Are you sure that's not 4.8M-BITS/second?   From what I understand of the
>technology, if they are using a single laser the upper limit on reliable
>data transfer is 5Mbits a second, or was so just a few months ago (ref:
>IEEE Spectrum, early this year?).

Yes. I am ABSOLUTELY SURE that it is 4.8 mBytes/sec, NOT mBits.

The maximum transfer rate of the Optidrive is not relevant, since (as I wrote
in that same article) the Optidrive has its own DMA channel and does not go
through the SCSI port.

Regardless of that, the maximum rate of a SCSI port is not dependant or
relevant to the speed of any individual device on it. For example, my Mac II
has a SCSI port which can absorb about 300 KBytes/sec. sustained. I can get
a DaynaFile SCSI Floppy unit which won't transfer more than about .5 mbit/sec.
I have a Wren III which can transfer about 1 MByte/sec. sustained. Naturally,
it doesn't go that fast when attached to the Mac (but it will when attached to
things like Suns).

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