The hard disk drive specifications that Apple supports are those published in
our literature. The Macintosh Internal Hard Disk HD40 SC is rated with an
average seek time of 30 milliseconds in literature dated February 1989. This
doesn't necessarily mean that all drives will be that exact speed -- just that
we claim they'll be at least that fast.
Our computers may ship with different hard drives during their product
lifetimes. In the case of the Macintosh SE/30, customers may have received a
Quantum, a Seagate, or a Sony. Each of these drives performs similarly, but
mild differences are detectable using certain benchmark tests. The most
noticeable difference in actual day-to-day operation would probably be the
unique sounds made by each drive: the overall performance should not differ all
that much.
Many factors influence which drive a customer receives with their Macintosh.
When a drive manufacturer is unable to produce adequate quantities for us,
we'll use another manufacturer. Sometimes drives are dropped from our approved
hardware lists for one reason or another, and others are added. It is almost
impossible to predict which drive a Macintosh will have.
The service situation is also difficult to predict. Our pool of service hard
drives changes over time, much the same as our pool of new product drives does.
All that is guaranteed is that our customers will receive replacement drives
that are compatible, and that will match or exceed our published
specifications.