#Hard drive boots
11-Oct-88 00:55:31
Sb: #15744-#Hard drive boots
Fm: John Draper 76703,4322
To: Richard Rae/SYSOP 76703,4253
Rick,
My response was based on the fact that the manufacturer says that to detect a
diskchange, you must step the drive. This tells me that there may be a reson
why you cannot use a simpler method, such as detecting a change on the write
protect status line. In fact, it is _probably_ the case that the drive needs
to be selected in order for the WP line to become 'visible' on the bus (all WP
lines are tied to one status line). Now the problem becomes selecting the drive
in order to read the status of the WP line, which will do no good unless one
can look at another line that was internally (to the drive) latched by the
change on the WP line.
The current implementation is definitely germaine to the discussion. CBM does
not make their own drives. They buy off-the-shelf drives as components, and add
a small amount of interface hardware to it. If the drive _must_ be stepped in
order to determine if a disk has been changed, then that's the only way they
can do it without modifying the drive itself.
That's all.. just pointing out that there might be a valid reason for the
current implementation, and why there may not have been any good alternatives
to it.
-larry