*BSD News Article 10410


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From: eoahmad@ntuix.ntu.ac.sg (Othman Ahmad)
Subject: Re: [386BSD] Creative Labs CD-ROM drivers - Any progress?
Message-ID: <1993Jan27.014525.20705@ntuix.ntu.ac.sg>
Organization: Nanyang Technological University - Singapore
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References: <1k4ei3INN6kl@mudos.ann-arbor.mi.us>
Date: Wed, 27 Jan 1993 01:45:25 GMT
Lines: 35

Marc Unangst (mju@mudos.ann-arbor.mi.us) wrote:
: In article <1993Jan26.073432.16561@ntuix.ntu.ac.sg> eoahmad@ntuix.ntu.ac.sg (Othman Ahmad) writes:
: >Why do say we are stupid when the ATBus version is surely faster than the
: >SCSI version?


: However, I doubt there's going to be any noticable performance
: difference at all.  Keep in mind that with a CD-ROM drive, the
: bottleneck is getting the data off the CD, not getting the data from
: the CD-ROM drive to the host.  The CD<->drive transfer rate is going
: to be 150K/s (or 300K/s, if you have one of the fancy double-speed

My figures are actually from CD disk drives called lasermate which I was led
to believe is a panasonic. It comes with 2 versions, the ATBUS(16-bit), and
SCSI(S$80 more expensive).
	Reading the specs, I notice that the transfer rate for the SCSI is
about 30%, 150K/s vs 170K/s(?). The access time of the SCSI is 0.5s vs 0.38 for
the ATBUS version. The drives look similar so must be identical mechanically
so the SCSI must have incurred a lot of overhead. Remember that the ATBUS is
not IDE, so virtually the PC has full access to the internals of the CDROM
circuit board.

: drives), no matter what you do with the host adapter; 150K/s is much
: lower than the maximum transfer rate of even an 8-bit card using
: programmed I/O.
YOu got the point. In fact I posted these observations to alt.cd-rom but
no response. I believe people do not read the specs and compare.


--
Othman bin Ahmad, School of EEE,
Nanyang Technological University, Singapore 2263.
Internet Email: eoahmad@ntuix.ntu.ac.sg
Bitnet Email: eoahmad@ntuvax.bitnet