A method for Replacing the Finder with an Application

by David Chaplin-Loebell, dcl@klatha.com

If you are writing a program which is to be used at a public access Macintosh, you may need to lock the public out from the use of the finder and other system functions of the Mac. This document describes a method for doing so. The idea of this method is that you will replace the finder with your application, so the finder will not be running when the Mac starts up. Additionally, unlike other methods of keeping the finder from running, the user will not be dumped to the finder if the application crashes. This is essential in a public-access environment like a museum or kiosk.

Note that these instructions also lock you out of the finder. Some public-access software which is mouse or touchscreen controlled relies on the lack of a keyboard on the public terminal, and leaves keyboard routes to the finder (like Command-Q to quit the application and relaunch the finder) available for maintenance. In this case, the finder simply is not there. Keyboard routes won't work. Make sure you have a startup disk or CD for that Mac model, so you can start up with the Finder if you need to do maintenance.

The first three steps of this method (detailed below) replace the finder with your application, by convincing the Mac that your application is the finder. This does have some additional implications. The most important are that both the apple menu items folder and the startup items folder are controlled by the finder. Nothing (except "About your application") will be on the Apple Menu. Likewise, your application will be the only startup item. If you wanted to use the startup applications folder to load a document or an extra application, you're out of luck. (However, since most museum exhibits and kiosks use custom applications, this is not a fatal problem. For example, if you're using HyperCard and intended before using this method to use the startup items folder to launch a specific stack, you can instead simply add a line to the "On startup" handler in your Home stack which says go to stack "your stack's name here". If you're using Macromind Director, use a projector file, rather than a movie file and the application. Other development environments have similar startup options.)

The fourth step of this method tells the application to restart the Mac in case of a quit (expected or unexpected) instead of shutting it down. This step may be omitted; if it is, a crash (or quit) will result either in a "It is now safe to turn off your Macintosh" dialog, or in the power being turned off, depending on your Mac model. This step has not been tested extensively, but it has worked for me every time I've tried it. It was supplied by:

* Note the above address is several years old and may be outdated.

INSTRUCTIONS

• Step 1. Remove the file "Finder" from the system folder. Place your application in the system folder.

  or Move every file in the system folder, except "Finder" into the folder with the application.

  Note: The second variation is preferable if the application expects to find ancillary files in the same folder as the application, or searches for them relative to that folder.

• Step 2. Rename your application "Finder".

• Step 3. Using ResEdit or some other tool, set the following attributes of your application (which, remember, is now called "Finder")

  Type: FNDR

  Creator: MACS

  Note: In ResEdit 2.1, this option is located on the file menu, and is called "Get File/Folder Info..."

• Step 4. Using ResEdit...

  Note: Remember, all ResEdit work should be done on copies only, for maximum safety.

  ...Open CODE resource ID#1. Do a Find/Replace for the following hexadecimal codes

  Find: 0001 A895

  Replace: 0002 A895

  Close the file, and save changes.

  Note: As mentioned above, this step has not been tested extensively. I have tested it on HyperCard 2.1, using several Mac models and several versions of System 7 up to and including 7.5. It has also been tested on a custom C program. It seems to work, but no guarantees. Yet another reason to use a copy.

Please let me know about any experiences you have with these instructions, successful or unsuccessful. Although I think they work (and have used them), I will make no warranties or promises. In particular, I don't have experience with the use of these instructions on Power Macs or under System 8.x. (I have received reports that they continue to work). This document is copyright 1993-1999, David Chaplin-Loebell (dcl@klatha.com) Please do not distribute modified versions without asking me.

This document was written while I was interning at the Franklin Institute, 20th & the Parkway, Philadelphia, PA 19103.

This page last modified 31 May 1996.