This week, an old Q&A-style Apple Support document:
Are there problems with connecting an external SCSI hard drive to the Macintosh Portable? I have a Macintosh Portable with an internal 40MB drive. When I tried to connect a 45MB external drive, the Macintosh Portable refused to boot. The “Sad Mac” icon came up with the error code: 0000000F 00000002.
The Macintosh Portable can access and use any external SCSI device that a Macintosh Plus can access. There may be an issue with the SCSI driver on the hard drive and compatibility with the Portable boot ROMs, but we do not have any information on this problem.