When you update the SCSI driver on a Macintosh SE, using HD20SC Setup 1.4,
the parameter RAM is affected in three ways:
1. It validates the SCSI ID for the internal drive. If it is determined not
to be a "reasonable" number, it is set to zero.
2. The time to wait for the internal drive to start up is checked and set, if
necessary.
3. There is a byte that is sometimes overwritten if the system crashes. If
this happens, the Macintosh won't start up from the SCSI drive. This byte
is reset if necessary.