ephraim@wang.UUCP (11/21/86)
Here's a problem you might meet if you're building your own SCSI cable. The Apple connector has 25 pins, a "real" SCSI connector has 50. All the odd SCSI pins are ground, so you might suppose that the easy thing to do is match up the 25 Apple pins with the 25 even SCSI pins (which include about 5 grounds and one NC), ignoring all those odd pins. If you do, your cable might or might not work. On some controllers, the manufacturer cheated with the even-numbered SCSI grounds: They're not connected! So, if you only use the even pins, your cable might not have any ground at all in it. The fix is to tie all the Apple grounds to *odd* SCSI pins. These really are grounded on every controller I've seen. Sadder but wiser, Ephraim Vishniac decvax!wanginst!wang!ephraim