dplatt@coherent.com (Dave Platt) (08/04/90)
I spent about fifteen minutes on the phone this afternoon, checking on whether the Toshiba XM-3201 CD-ROM drive would work properly with a Mac IIfx (I have one of the former, and am thinking of upgrading to the latter in the near future). I spoke to the folks at Optical Media International (the authors of the driver which Toshiba OEMs for sale with the XM-3201) and with Toshiba's CD-ROM tech support group in San Jose. 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. The problem is apparently due the high speed of the IIfx SCSI bus, according to the gentleman at Toshiba to whom I spoke. He gave me the name and number of someone at Toshiba's main disk-products department who can apparently provide more-detailed information; I'll phone him on Monday. I was assured that Toshiba is actively pursuing a solution to the problem. 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).
minow@mountn.dec.com (Martin Minow) (08/05/90)
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
dplatt@coherent.com (Dave Platt) (08/08/90)
In article <65766@coherent.coherent.com> I wrote: > The consensus: at the moment, the XM-3201 does _not_ work reliably with > the IIfx. Since I posted the above note on Friday, I've had a long and fruitful conversation with one of Toshiba's CD-ROM hardware gurus, and a shorter and equally fruitful conversation with one of OMI's software developers. What I learned is as follows (quotations below summarize what I was told; they are not exact): - The Toshiba XM-3201 CD-ROM drive does indeed have some problems working with the Macintosh IIfx. - The problems are due to the high speed of the IIfx SCSI chip... the IIfx is overrunning the CD-ROM drive processor somehow. The problem affects the XM-3201 model, and I'm told that some hard-disk manufacturers have had similar problems with their drives. "The IIfx SCSI implementation is much faster than anything we've seen before." - The problem is _not_ due simply to electrical noise, ringing, or reflections on the SCSI bus (due to improper termination of the bus, incorrectly-wired cabinets which create unterminated "stubs" on the bus, etc.). The problem can show up even if the bus is wired and terminated according to the SCSI-1 specifications, using a Mac IIfx terminator at the far end of the bus, and is electrically "clean" as shown by a TDR analysis. - It's possible to work around the problem by installing a long SCSI cable between the Mac IIfx and the XM-3201. This apparently introduces enough delay into the SCSI bus to keep the XM-3201 controller from being swamped. "8 feet of cable usually works; go for 10 or 12 feet if you can. The long cable must be between the Mac and the drive... putting the long cable on the far side of the drive won't help. 10 feet of ribbon cable, folded back and forth in a box, with a 'D' connector on each end, is one way to do it. I wouldn't call this a 'fix'... more of a 'band-aid'... but it does seem to work." - Toshiba is looking into better solutions for the problem. It's uncertain whether they'll choose to update the XM-3201 hardware to support the IIfx... a circuit modification has been developed, but in its current form it's not easy to install and won't allow the drive cover to fit back into place. Toshiba might decide to wait for the next model (XM-3300 series) to come out, and make sure that this new design will work correctly with the IIfx. "It's really a matter between the marketing people here, and the technical people in Japan. Our relationship with the manufacturing-and-design people in Japan is similar to that of a big O.E.M." - Either version 1.2, or version 1.3.1 of the Toshiba driver (OEM'ed from OMI) should work OK with the IIfx. Version 1.3 might not mount discs properly. So... if you have a CD-ROM drive which uses the Toshiba mechanism, you can probably use it with a IIfx by installing a long SCSI cable. It's not an ideal solution, but anecdotal reports suggest that it does work. If you have a IIfx and are thinking of buying a CD-ROM drive based on the Toshiba mechanism, you might want to make sure that you can return the drive for credit if it doesn't work properly with your IIfx.
esmith@goofy.apple.com (Eric Smith) (08/08/90)
In article <66179@coherent.coherent.com> dplatt@coherent.com (Dave Platt) writes: In article <65766@coherent.coherent.com> I wrote: > The consensus: at the moment, the XM-3201 does _not_ work reliably with > the IIfx. Since I posted the above note on Friday, I've had a long and fruitful conversation with one of Toshiba's CD-ROM hardware gurus, and a shorter and equally fruitful conversation with one of OMI's software developers. What I learned is as follows (quotations below summarize what I was told; they are not exact): - The Toshiba XM-3201 CD-ROM drive does indeed have some problems working with the Macintosh IIfx. - The problems are due to the high speed of the IIfx SCSI chip... the IIfx is overrunning the CD-ROM drive processor somehow. The problem affects the XM-3201 model, and I'm told that some hard-disk manufacturers have had similar problems with their drives. "The IIfx SCSI implementation is much faster than anything we've seen before." - The problem is _not_ due simply to electrical noise, ringing, or reflections on the SCSI bus (due to improper termination of the bus, incorrectly-wired cabinets which create unterminated "stubs" on the bus, etc.). The problem can show up even if the bus is wired and terminated according to the SCSI-1 specifications, using a Mac IIfx terminator at the far end of the bus, and is electrically "clean" as shown by a TDR analysis. If the problem is not noise, ringing, or reflections, does their driver do Macintosh-style "blind reads"? From the description above it sounds as though the problem is in the handshaking. I would think that Using standard (non-blind) accesses would solve this problem, since then standard SCSI-1 handshaking is used. The handshaking is supposed to make SCSI independent of the maximum transfer rate of both the initiator and target. Disclaimer: My job has nothing to do with SCSI. I just have hacked around with it in my copious free time (ha, ha). So I probably don't know what I'm talking about. -- Eric L. Smith Opinions expressed herein do not necessarily reflect those esmith@apple.com of my employer, friends, family, computer, or even me! :-)
kam@dlogics.COM (Kevin Mitchell) (08/08/90)
I'd see if an Apple dealer can come up with a new cord. The cord used on the Mac has stranded wires in it -- most telephone cords use extremely fine wire or ribbon wrapped around cotton thread. The Mac keyboard draws its power through the cord, and if you used a telephone cord, the extremely thin wires would overheat. The same goes for most other keyboards as well. -- Kevin A. Mitchell (312) 266-4485 Datalogics, Inc Internet: kam@dlogics.UUCP 441 W. Huron UUCP: ..!uunet!dlogics!kam Chicago, IL 60610 FAX: (312) 266-4473