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Building a Sys7 Emergency Disk

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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               
          -5696
DRVR      .DSP .MPP .XPP .ATP
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     
          -5696:-5694
STR       -16410:-16409       -5786
STR#      -16985    -16491    -16484:-16482       -16413
          -16411    -16409:-16408       -6079     -6045
          -5856     -5792:--5787        -5759     -5696
          -4096

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 System.

6) Now use Resedit on the System file on the minimum system floppy as described in step 8 above. Finally do step 9.