MPW 3.0: Conflicts Caused by INITs Misusing PBHSetVol

Apple Tech Comm has found a problem in a number of third-party INITs that cause the MPW Installer to fail. This problem is the result of these products doing a HSetVol by calling PBHSetVol. Macintosh Technical Note 140, "Why PBHSetVol is Dangerous," warns against using PBHSetVol. This problem has been reported most frequently with TOPS from TOPS, a Sun Microsystems Company.
When you try to run the MPW Installer while running a third-party INIT, you get an error saying the "DoIt" script cannot be found. The message appears when an INIT uses PBHGetVol to get and save the working directory and then tries to restore the working directory using PBHSetVol. The result is that such an INIT sets the working directory to the root of the volume containing the installation volume. Note: Any mention of installation in this article refers to the procedure outlined in the "Macintosh Programmer's Workshop Development Environment Reference, Volume 1." Here are three workarounds for this problem.

First, you can install MPW by hand and forego the MPW Installer. However, this does not stop problems caused by INITs that use PBHSetVol. Any INIT that uses PBHSetVol interferes with the setting of the working directory any time you insert a disk while running MPW. After inserting a disk, the problem manifests itself when:

In both of these cases, a "directory :" command (as given in step 2 below) restores your environment.

Second, you can install MPW without the INIT running. In the case of TOPS, restart while holding down the Command key. During the restart process, TOPS will bring up a dialog asking if you want to install TOPS. Answer no, and proceed to install MPW 3.0.

Third, you can modify the installation script by following the procedure described below:

References: See "Macintosh Programmer's Workshop 3.0 Errata: MPW Installation Problems;" revision date: March 13, 1989

The following Tech Info Library article can help you find the Tech Note mentioned here:

Article 24493: "Apple Tech Notes: What They Are, Where To Find Them"
Published Date: Feb 18, 2012