Will a 29ms hard drive perform twice as fast as a 65ms hard drive if both
are run on an Apple IIGS with the Apple SCSI card? In other words, is the
hard drive the slower component, or the Apple IIGS with the Apple SCSI card?
The maximum data transfer rate for the SCSI bus is 1.25 MBytes per second. If
the disk accesses the data faster than that, it is not apparent to the user.
The determining factor for data transfer is system overhead. In this case,
the system is the slower component.
System overhead consists of: operating system timings, interface timings,
and the interleave factor for the disk (which is 3 to 1 for the Apple IIGS).
If the 65ms drive is waiting for the Apple IIGS system, then changing to a
29ms drive will probably not increase performance.