Apple II
Technical Notes
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                                                  Developer Technical Support

SmartPort
#9:    Apple II SCSI Errata

Written by:    Llew Roberts                                         July 1990

This Technical Note documents SCSI-specific anomalies that were discovered in 
the development of the Apple II High-Speed SCSI card.
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During the testing of the Apple II High Speed SCSI Card, several SCSI-related 
issues of interest to developers were discovered.  Most of these issues 
directly relate to SCSI devices with removable media.

If a CD-ROM has a bad directory, the firmware hangs because it gets a "Read In 
Progress" error.  There is no timeout.  The system can be recovered if the CD-
ROM is manually ejected.

If the media is ejected while a SmartPort DIB Status call is in progress, the 
call returns with incorrect results (it reports DISKSW and that the block 
count of the device is zero).  In order to avoid this conflict, bracket the 
DIB Status call with the SmartPort SCSI specific Control Calls Prevent Removal 
($1A) and Allow Removal ($1B).

A SmartPort FORMAT call, in some cases, does not update the DIB correctly to 
reflect the new or changed partition map.  If a SmartPort Init call is always 
made immediately after the FORMAT, the DIB is rebuilt correctly.  Note that 
after formatting a tape, the tape should be removed from the SCSI tape drive 
before an Init call is made.  An Init call causes the tape to rewind, hanging 
the system with no time-out until the rewind is complete.

Further Reference
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  o  Apple IIgs Firmware Reference
  o  Apple II High-Speed SCSI Card Technical Reference

