Floppy Drive Port: Maximum Power Load (11/94)


I am interested in the Integrated Data Systems IDS-WIP series drive. It is a low-power, compact SCSI drive that gets its power from the external, floppy port.

Are there any possible problems with this drive? Would it invalidate Apple's warranty? They mentioned in its specifications that it uses from .25 to 1.5 watts maximum draw, depending on the size of the hard disk.

The power budget of this port varies slightly with each of the Macintosh models, but the worst-case scenario follows. The combined load of all devices connected to the floppy drive ports shouldn't exceed the following:

+5 700 milliamps
+12 600 milliamps
-5 10 milliamps

Apple typically discourages using the floppy port in the way you describe. These ports were designed to support the 400K, 800K, and the 1.44MB Apple disk drives. The older Macintosh computers also had ROM support for the Apple HD20-- which provided its own power.

Because the drive you describe requires no physical modification to the Macintosh, powering a SCSI drive in this fashion would not void the warranty--unless the damage caused to the Macintosh is traced back to the drive.


Article Change History:
21 Nov 1994 - Reviewed for technical accuracy.

Support Information Services
Published Date: Feb 18, 2012