Re: 2 q's : Dead Vulcan & gs <--> mac interconnection

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

In article <AJMCD4.61.302192DB@cfs02.cc.monash.edu.au>,
Andrew Mc. Donald <AJMCD4@cfs02.cc.monash.edu.au> wrote:
> 
> 1.  A friend of mine called me the other day saying that his 40 meg Vulcan hd 
> had died.

I can't help with this one, sorry.

> 2.    He also wants to hook his gs up to his Macintosh LC, so that his gs can 
> access the Mac's hd.  How is this possible??

It can be done, but it is a reasonably complicated procedure.

What you need to do is to set up an AppleTalk network connection
between the two computers.  Both machines have a LocalTalk-compatible
serial port, and if you aren't going to be connecting any other
devices, you can use a simple Mac-to-ImageWriter serial cable between
them.  If you want to connect other devices as well, you'll need a
proper cabling system: either Apple's LocalTalk (expensive) or a
third-party alternative such as PhoneNet.

The second step is to set up the appropriate software on each machine.

Before going any further, I should point out that the end result is
not particularly fun to use.  Transferring files over a LocalTalk
network is about the same speed as using a 3.5" floppy drive (at best).

It is also not possible to boot the IIgs from the Mac's hard drive,
unless you get the full AppleShare file server software for the Mac,
which is very expensive.  You also have to be careful to get the right
version - old versions don't work with System 7, and the latest
versions no longer support booting an Apple II over the network.

The simplest type of connection allows simple file access to the Mac's
hard drive from the IIgs.  In effect, you have a non-bootable slow
hard drive.

On the Mac side, you need to install and configure the "File Sharing"
option included with System 7 and later, make sure AppleTalk is
enabled, turn on File Sharing, and enable sharing for the main hard
drive volume.  You may also need to set up a user account for use by
the IIgs, via the "Users and Groups" control panel.

On the IIgs side, you must have AppleTalk enabled in the Control Panel
for the appropriate port.  For a ROM 1 IIgs, set slot 7 to "AppleTalk"
and slot 1 to "Your Card".  The network cable should be plugged into
the printer port.  (You can use the modem port instead, by setting
slot 1 to "Printer Port" and slot 2 to "Your Card".)

For a ROM 3 IIgs, set slot 1 or 2 to "AppleTalk", corresponding to the
port you have the network plugged into.

You then need to create a IIgs system disk that contains AppleShare
access software, and boot from this disk.  This can be done using the
System 6.0.1 installation disk set.  The big catch: AppleShare support
takes up so much space that there won't be enough space left on the
disk to include Finder.  You will need to use a smaller program
launcher, or run Finder from a different disk.

Network access from a IIgs really works best if you can either boot
from the Mac file server, or if you have a hard drive on the IIgs.

To access the server, you must boot into GS/OS from a system disk with
the AppleShare client software installed.  You can then access the
server from GS/OS and from ProDOS-8.  Note: ProDOS-8 access is
somewhat restricted: the Mac's hard drive must be named to comply with
ProDOS file name restrictions, as must any directories that are to be
accessed from ProDOS-8 programs.

> Can the GS, mac and hd be joined in a scsi chain?  

Yes, but it is definitely not safe to do this.

The only physical requirements are that you are using a Mac SE or
later machine (a Plus might work, but I wouldn't trust it), the Apple
II is using an Apple SCSI card (preferably a High-Speed one) - a
RamFAST will NOT work - and the Apple II must be set to a different
SCSI ID from the hard drive and the Mac (Macs are usually fixed at
SCSI ID 7, and this is also the default for the Apple II SCSI cards.)

The computers cannot communicate with each other in this configuration
(well, they possibly could if someone wrote some software to support
this, provided there are no hardware or firmware restrictions in
either machine preventing this type of operation).

The only possible application is to share peripherals, and this is not
safe.

The computers are not aware of each other, and in particular are not
aware of any changes made to the contents of the hard drive.  If they
are both switched on and actively using the hard drive, it will take
next to no time to corrupt the contents of the hard drive, as each
computer will try to write data to the same areas that the other one
is using, both with try to update directories without the other
knowing about it, etc.

I know of someone who tried to do this, and he kept complaining that
he was getting parts of directories appearing in his AppleWorks
spreadsheets!

It is only safe to share a hard drive in this manner if there is some
mechanism preventing the computers from writing to the same partition,
and they are aware of changes made by the other computer (this is not
likely to be the case - caching on both machines may mean that changes
made by one computer will not be noticed by the other one).

It is only completely safe if neither computer attempts to read from
partitions being written by the other, or if both computers have
read-only access to a partition.

One example of this might be a large hard drive with HFS and ProDOS
partitions.  The Mac would have to be set up to NOT support access to
the ProDOS partition, and the IIgs would have to avoid the use of the
HFS FST.  It wouldn't be ideal: GS/OS would alert you that there was
an HFS partition on the drive, and tell you that you should install
the HFS FST to access it.  The Mac would probably just ignore the
ProDOS partition.  This doesn't help much with sharing files between
the machines.

Another possibile application would be an external hard drive that is
shared between a Mac and a IIgs.  Only one computer could be switched
on at a time, and it would then have exclusive access to the hard
drive.  This isn't possible with a Mac's internal drive, since it is
powered from the machine.

In short, don't do it.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand