Re: Help with IIgs

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

Nathan Mates <nathan@visi.com> wrote:

> In article <32B26DB3.7D8F@unixg.ubc.ca>, Ben Lai  <benlai@unixg.ubc.ca> wrote:
> >> Try to get Iomega's Zip Drive. It comes with 100 MB disks and allows you
> >> to easily exchange large amounts of data with other Zip drive users.
> 
> >Since GS/OS 6.0.1 can read MS-DOS files, so I guess a IIgs can read both
> >MS-DOS or Mac formatted Zip disk, is this correct?  
> 
>    Mac formatted Zip disks are fine, but I think that PC Zip disks
> could be a problem. PCs had to be different and partition scsi drives
> differently than Apples [not sure if partitioning was ANSI spec'd and
> one or both sides decided to flout it, or what]

The Mac/Apple II partitioning system was first used about 1985, as far
as I can tell.  It is only briefly documented in Inside Mac volume 4
(Mac Plus, early 1986), and is fully documented in Inside Mac volume 5
(Mac SE and later, 1987).

The PC's partitioning scheme was used in the IBM AT (1986), and possibly
earlier - I don't think I've ever seen an IBM XT (or XT clone) with a
partitioned drive.  If it was supported by the original XT, then it
dates back to 1983ish.

(Can anyone pinpoint these dates more precisely or provide more
information about the origin of either method?)

I don't know if either method is an ANSI standard.


In any case, the PC's scheme is specific to the PC - it has 8086 boot
code in the first sector (this could be ignored by other platforms), and
is closely related to the physical structure of the disk (the first
track of the first cylinder has the partitioning table, and partitions
can only be started on cylinder boundaries, if I remember right).  It
has a peculiar distinction between "primary" and "extended" partitions:
a drive can only have one active primary partition (other primary
partitions are not addressable).  An extended partition can be
subdivided into logical partitions.

MS-DOS can only boot from a primary partition, but most other PC
operating systems can boot from either type.


The Mac's scheme is more flexible.  It has a driver mechanism which is
able to support multiple host processors (not used by the Apple II), and
a well-defined mechanism for identifying the file system which owns each
partition.  Partitions may be allocated starting at any block.

> so I'd think that the SCSI card might not recognize the partitions. If the
> SCSI card can deal with the Zip's formatting, you should be able to use the
> MS-DOG FST to read it.

Speaking from experience: a PC-formatted ZIP disk is _not_ recognised by
the IIgs (with the MS-DOS FST installed).  You can partition it, of
course.

In theory, it should work with Peter Watson's MS-DOS utilities, but I
didn't try.

>    Thanks to Win95 going and changing the file structure a bit at the
> start (the VFAT long filename extensions), you could probably read off
> files from this disk no problem, but the MS-DOS FST would muck up the
> VFAT tables if you tried to write to it.

The MS-DOS FST is read only, so this is a moot point.  MS-DOS Utilities
would certainly cause problems.

> Should you have Win95 Service Pack #2 installed with the
> FAT32 support, that'll probably store data to a Zip disk in a way that
> the MS-DOS FST couldn't deal with at all.

No argument there.  MS-DOS Utilities wouldn't handle it either.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand