Re: making a boot disk on iigs

[Jeff Blakeney <CUTjblakeney@sympatico.ca>]

On Mon, 16 Feb 2004 17:32:13 GMT, Rubywand <rubywand@swbell.net>
wrote:

>John K writes ...
>> 
>> forgive my newbie questions....
>> 
>> I just got a iigs and want to copy its system disks.  I can copy the files
>> easily enough but the disk doesn't boot.  What do I have to do to
>> a disk to make it bootable?
>> 
>> I have 20 years experience with PCs but the terminology & function
>> of apple systems are completely new to me!
>
>     The problem you're running into is the difference between a ProDOS
>diskette which is "formatted" and one which is "initialized".
>
>     Often, a "formatted" diskette will have everything necessary for saving
>files, etc.; but, it will lack the ProDOS boot block code. An "initialized"
>ProDOS diskette will be formatted _and_ have the boot block code. 

There is a difference between formatting and initializing, on the IIgs
at least, but I'm not sure you quite have it.  Formatting will write
the boot blocks, empty directory blocks, the appropriate block table
for the disk being used and will write blocks of zeros to all the rest
of the blocks on the disk.  Initializing will only write the boot
blocks, empty directory blocks and the appropriate block table for the
disk being used and doesn't write anything to the other blocks on the
disk.

Initializing is much faster, especially on large volumes like hard
drives but it does leave a lot of non-zero blocks around and if you do
a volume backup, all those non-zero blocks will take up extra space
that could be compressed to practically nothing if they were zero
blocks.  This is why, when making ShrinkIt disk images (or any disk
image for that matter), it has always been highly advised that you
format a blank disk, copy the files that you want on that disk image
to the freshly formatted disk and then make the image of that.  You
get rid of all the unused, non-zero blocks and can allow the image to
be compressed more.

 Initializing also leaves you the opportunity to restore what you had
on that volume if you accidentally initialize it whereas formatting it
will wipe everything on the drive leaving no opportunity to recover.

If I remember correctly, John's question was answered adequately by
others.  All ProDOS disks are bootable with only a few exceptions.
You just need the proper files on the disk to make it do something.
PRODOS and BASIC.SYSTEM on a freshly formatted or initialized disk
will boot into Applesoft.

>     The /RAM5 RAM disk you can set up on a IIgs is an example. When it's
>created it will be formatted; but, it will not have the boot block code. To
>add the boot block, you can take the extra step of Initializing it.

This is one of the exceptions to all ProDOS disks being bootable.
This started back when the /RAM disk was created using the extra 64KB
of a IIe with extended 80 column card or later machine.  Whoever wrote
the /RAM driver decided to save some space by not putting the boot
blocks on the RAM drive.  Why this continued on to the /RAM5 driver, I
don't know.

-- 
 Jeff Blakeney - Dean of the Apple II University in the
                 Apple II Community on Syndicomm.com
 CUT the obvious from my address if you want to e-mail me