Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!sdd.hp.com!decwrl!bacchus.pa.dec.com!decatl!shlump.nac.dec.com!mountn.dec.com!minow
From: minow@mountn.dec.com (Martin Minow)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Toshiba XM-3201 and the Mac IIfx
Message-ID: <1819@mountn.dec.com>
Date: 5 Aug 90 02:41:19 GMT
References: <65766@coherent.coherent.com>
Reply-To: minow@bolt.enet.dec.com (Martin Minow)
Distribution: comp
Organization: Digital Equipment Corporation
Lines: 47

In article <65766@coherent.coherent.com> dplatt@coherent.com (Dave Platt)
writes about the Toshiba XM-3201 CD-ROM on the Mac IIfx.
>
>The consensus: at the moment, the XM-3201 does _not_ work reliably with
>the IIfx.  Some people have had problems with this configuration;  some
>of those people have been able to work around the problem by using a
>long (6') SCSI cable.
...
>So... if you have a IIfx, or are planning to upgrade to one, be aware
>that the XM-3201 mechanism may not work with it.  This mechanism is
>marketed directly by Toshiba, and is also used in many of the
>third-party CD-ROM drives (e.g. the CD Technology Porta-Drive,
>MicroTech's CD600, and several others).

I took the case off of a Toshiba XM-3201B in order to interface it to a
non-standard SCSI cable (professional programmer: don't try this at home)
and have a gut feel that the problem is not due to a problem with the actual
drive but with the internal cable Toshiba uses to connect the drive
mechanism with the cable sockets on the back of the drive case.  The
Toshiba cable is connected
	scsi connector	>-+
			  |
	scsi connector	>-+------> Toshiba drive

Instead of the correct
	scsi connector	>-------+
			   	|
	scsi connector	>-------+> Toshiba drive

Toshiba's cable (which is marginally cheaper to manufacture) leaves
a long (well, four inch) "stub" connected to the SCSI bus, which is
prone to reflections.

You *might* try connecting the Toshiba at the end of the bus, using an
in-line terminator connected to the scsi cable:
     nothing connected here >-+
			      |
	cable ->>terminator>>-+------> Toshiba drive
Another possibility would be to connect the Toshiba at the end of the bus
and use an internal terminator (I don't remember if this can be done; doing
this will almost certainly void your warranty.  Also, you're supposed to
use the Mac FX terminator, remember.)

The above does not express the position of Digital Equipment Corporation.

Martin Minow
minow@bolt.enet.dec.com