boogles@athena.mit.edu (Brian K Zuzga) (12/08/90)
We are looking to purchase a CD ROM drive for a MAC IIFX. I was looking for any suggestions or caveats that you might have. Any help you could provide would be appreciated. The safe thing to do would be to get an official Apple CD-ROM drive, but it allegedly is an old design and quite slow. What should I look out for in regards to the SCSI problem with the FX? Thank you for your time. Brian Zuzga boogles@athena.mit.edu
beecher@cunixf.cc.columbia.edu (Ben Beecher) (12/09/90)
In article <1990Dec8.021112.25629@athena.mit.edu> boogles@athena.mit.edu (Brian K Zuzga) writes: >We are looking to purchase a CD ROM drive for a MAC IIFX. I was >looking for any suggestions or caveats that you might have. Any >help you could provide would be appreciated. The safe thing to >do would be to get an official Apple CD-ROM drive, but it >allegedly is an old design and quite slow. What should I look >out for in regards to the SCSI problem with the FX? Thank you >for your time. > >Brian Zuzga boogles@athena.mit.edu Avoid the Porta-Drive CD-ROM drive by a Toshiba subsidiary (C D Technology) model number T3201 in the TXM-3200 series. Microsoft had a special deal last summer where you could buy the Porta-Drive and Microsoft Office on a CD for $1000. When connected to a IIfx the drive works *ONLY* when daisy chained off another SCSI device. In my case I have it daisy chained off a MicroNet 45M removable disk drive. The drive will not work if connected directly to a IIfx. Another problem is the position of the two 50-pin SCSI sockets on the back of the drive. They are so close together that you have to bend the sockets apart to fit the plugs in the sockets. A really bad design. I have had no problems with the drive mechanism, however. It reads CD's like a champ. Ben Beecher beecher@cunixf.cc.columbia.edu Network Planning 212-854-7439 Columbia University
dplatt@coherent.com (Dave Platt) (12/09/90)
In article <1990Dec8.193547.991@cunixf.cc.columbia.edu> beecher@cunixf.cc.columbia.edu (Ben Beecher) writes: > Avoid the Porta-Drive CD-ROM drive by a Toshiba subsidiary (C D > Technology) model number T3201 in the TXM-3200 series. I don't believe that CD Technology is a Toshiba subsidiary. Rather, they're an OEM who purchases the XM-3201 mechanism and stuffs it in a box of their own design. Toshiba sells the same mechanism in a somewhat larger box with an integral power supply (for a somewhat higher price). Several other OEMs also use the XM-3201 mechanism. > When connected to a IIfx the > drive works *ONLY* when daisy chained off another SCSI device. In my > case I have it daisy chained off a MicroNet 45M removable disk drive. > > The drive will not work if connected directly to a IIfx. According to the people at Toshiba to whom I've spoken, it's not really a matter of daisy-chained vs. direct-connected. Rather, there's a timing problem in the XM-3201 SCSI controller, which shows up only when the device is talking to a very fast SCSI initiator such as a IIfx. The workaround suggested to me was to connect a long SCSI cable between the IIfx and the Toshiba... 8 feet of cable is sometimes enough, 10 feet almost always works, 12 feet seems to be quite reliable. This long cable apparently introduces enough extra delay into the SCSI handshaking to permit the controller to work reliably. [It sounds like a race condition with a narrow window... an extra 6 feet of wire would add about 12 nanoseconds of delay, or roughly the equivalent of one gate delay in the circuit.] This problem showed up in my configuration (Mac II, upgraded to a IIfx, connected to an XM-3201 mechanism in a homebrew case). Adding a 6-foot SCSI extension to the existing 6-foot cable cured the problem. Ben: I suspect that by daisy-chaining the Toshiba off of the back of your MicroNet, you moved it far enough away from the IIfx to avoid the race condition. > Another > problem is the position of the two 50-pin SCSI sockets on the back of > the drive. They are so close together that you have to bend the > sockets apart to fit the plugs in the sockets. A really bad design. That does sound like a goof! > I have had no problems with the drive mechanism, however. It reads > CD's like a champ. I've had similarly good results. It reads both CD-ROMs and audio CDs quite nicely. It has successfully tracked every audio CD I've put in it, including one which I believe was somewhat out of spec (my CAL Icon wouldn't track it reliably).