Re: 3 3.5" drives?

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4lpmhv$etj@asia.lm.com>,
Matt Portune <mportune@telerama.lm.com> wrote:
> A friend of mine came across a third 3.5" drive, but has reported it as 
> not working.  He has no hard drive, and only 1.25 megs of RAM, so he uses 
> 2 drives extensively.  I've never had any experience beyond 2 drives 
> daisy chained on a GS.  Does it work?

No, it doesn't.  There are only two drive select lines available for
the Apple 3.5 Drive, so a third drive will not be selected (it might
be selected at the same time as the first or second drive, depending
on how the daisy-chain board in the drive has been wired, but the data
will not get through, and might interfere with the other drive which is
selected).

There is no problem using a third Apple 3.5 Drive if you have another
controller (e.g. an Apple 3.5 Disk Controller Card, a.k.a. SuperDrive
Card, or a Universal Disk Controller) - just connect two to the IIgs
disk port, and the other one to the other controller.


It is possible to connect more than two UniDisk 3.5 drives (or one or
two Apple 3.5 Drives followed by any number of UniDisk 3.5's).  The
theoretical limit is 127 drives, but power supply and signal loading
probably restricts you to four or six drives in total off a single
chain.

(The UniDisk 3.5 is an intelligent SmartPort device, which uses a
packet-based protocol to transfer data to and from the computer.  A
7-bit byte is used for addressing the drive.)
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand