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Building a Sys7 Emergency Disk

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From: [email protected] (Rich Ragan)
Subject: Building a Sys7 Emergency Disk 
Date: Mon, 10 Feb 92 14:12:54 PST 

The following description should probably go into the archives
rather than just be a one time posting.

Thanks, Rich Ragan ([email protected])

Everyone should have a "In Case of Emergency, Break Glass System 
Floppy Disk". It should contain a bootable system and a good disk
recovery utility such as Norton, SUM, etc. However, with the advent
of System 7 this has become hard. A minimal System and Finder leaves
insufficient space for the disk recovery tools.

The following cookbook will allow you to build an emergency recovery
disk for your Macintosh. Here is how to proceed.

First you want to be careful not to mess up your own system. The 
installer will not let you install on the disk with the currently
running system. Most users have only one floppy drive and only
one hard disk. Therefore, if you install floppy to floppy you will
enter what is often called "toaster mode" where Mac floppies pop
like toast from the drive in a seemingly interminable sequence.
Therefore, a "better" way is to install floppy to hard drive. But
this can easily end up replacing your current System 7 version with
a minimal one -- something you probably don't want to do. Therefore,
the following procedure let's you avoid this. If you are uncomfortable
with this or have two 1.4MB floppy drives, try the alternative
procedure at the end.

1) Reboot your system from the installer floppy. 
2) Open the System folder on your hard drive (not the floppy) and
   drag the Finder into a folder (Extensions will do). Now rename
   your Hard Drive System Folder to another name (say My System Folder).
   The MAC determines which is the system folder by finding one that
   contains both a System file and a Finder. By splitting them up
   you make your System Folder back into an ordinary folder. You want
   to rename it because the Installer will create a new folder named
   System Folder.
3) Double click the installer on the floppy. Follow the normal
   System 7 install procedure. Select installation on the hard disk
   where you just renamed your System Folder. Next, click the
   Custom Install button and scroll down the list of things you can
   install until you find "Min System for your-machine-kind".  Select
   this and click Install (not Easy Install). 
4) When the install completes you will have a new System Folder on
   your hard drive with a mimimum system in it. This amounts to a
   System file, a Finder and a couple of folders.
5) You should be able to reboot your machine and have it start up
   successfully from this minimal system. If, for some reason, it
   will not restart your emergency recourse is to reboot from the
   installer floppy and go to step 7) below to restore your previous
   System. This should not be necessary, however.
6) After the reboot, take a freshly erased 1.4MB floppy and copy just
   the minimal System file you have built on the hard drive to the
   floppy. Do not copy the Finder or any of the folders. The file
   named System should now be the only thing on your floppy.
7) Now you are ready to restore your previous system, having generated
   a minimal system. Open the minimal System Folder, drag the Finder
   into the Control Panel folder. This will split the
   System and Finder and as described above make this a non-System Folder.
   Rename your mini System Folder to something like MinSysFolder. Now
   rename your previous System Folder back to what it was (probably
   System Folder). Open it and move the Finder from the Extensions
   Folder back into the System Folder. Now close the System
   Folder. You should see the special icon denoting the System Folder
   appear on it. If it does, all is well. The System now accepts it 
   as THE System Folder. If it does not appear, open and close the
   System Folder once more. Sometimes this will do the trick. If not,
   try dragging the Finder from the System Folder to the Desktop. Now
   close the System Folder and drag it back into the System Folder.
   This has sometimes been necessary to force recognition. Once you
   get a System Folder icon you are ready to reboot using your original
   full System 7 environment.
8) Now you are ready to put the Minimal System file on the floppy onto
   a "quick weight loss diet". You will need ResEdit to do this. Start
   up ResEdit and delete the following resources types/numbers from
   the Minimal System file. If you don't know how to use ResEdit, find
   someone who does (i.e., kids don't try this without adult supervision).

   The essence of the shrinking procedure is that there is a lot of good
   stuff in the System that is not needed when more pressing things are
   going on (like recovering a crashed hard disk). Therefore, you will
   delete these nice but superfluous parts of the Minimal System file.
   The following list of resource type and numbers appear to be safely
   deletable for a minimum system. Don't try to construct a system you
   run everyday this way. For example, transcendantal functions are
   deleted (hopefully no disk recovery packages needed to compute sines).
   Ranges of resources to delete are separated by a colon.

   Major space gains come from deleting the AppleTalk DRVR's and the
   packages (PACK 5, and 9-15). For example, PACK 14 is the Balloon
   Help stuff. Each PACK owns other resources which can be removed
   after the PACK is gone. The owner of a resource can be seen by
   selecting the resource and doing a get resource info. Thus if you
   have deleted PACK 14 you can safely delete all resources it owns
   (like hdlg, hmnu, DITL, DLOG, etc.). Of course you must not try to
   use balloon help after that. Rather than make you think about it
   here is a list of things you can delete to build a minimum system.
   You may not have all the things that are in the list depending on 
   which machine you built the minimum system for. 

ALRT      -16407:-16406       -5758
DITL &    -32512:-32509       -16492:-16491       -16483: -16482      
DLOG      -16409              -16407:-16406       -5856
          -5792:-5786         -5760               -5758               
FKEY      all
hdlg      all
hmnu      all
icl4      all
ics#      all but 16386 (Apple Icon)
ics4      all
ICON      -16492:-16487
ics8      all
PACK      9:15 and 5 (if present)
PICT      -16482:-16485       -5790     -5789     -5760     
STR       -16410:-16409       -5786
STR#      -16985    -16491    -16484:-16482       -16413
          -16411    -16409:-16408       -6079     -6045
          -5856     -5792:--5787        -5759     -5696

9) After quitting from Resedit and saving the changes you
   should have a floppy with a lot of space on it. Now put
   your Disk Recovery utility on this disk as well. Rename
   the Disk Recovery Utility to have the name Finder. It will
   now be run immediately when you boot from this floppy since
   it is thought to be the normal Finder.

Alternative procedure for floppy only building.

1) Boot using installer floppy. Eject installer floppy
   by dragging to trash. Insert freshly erased 1.4MB
   floppy. Now eject it using Eject menu item. Reinsert
   installer floppy and run the installer.
2) Select installation on the empty 1.4MB floppy disk
   Next, click the Custom Install button and scroll down the 
   list of things you can install until you find 
   "Min System for your-machine-kind".  Select
   this and click Install (not Easy Install). Follow the
   disk swap instructions. 
4) When the install completes you will have a new System Folder on
   your floppy disk with a mimimum system in it. This amounts to a
   System file, a Finder and a couple of folders.
5) Drag the Finder and all folders in the System Folder on the 
   Minimum System floppy to the Trash.Leaving only the file named
6) Now use Resedit on the System file on the minimum system floppy
   as described in step 8 above. Finally do step 9.