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Mac IIfx / System 7.1.2 / Gremlins


Well-known member
As part of my IIfx restoration project, I had installed System 7.1.2, and I had run into strange crashes running Adobe Photoshop 3.0.5 with that setup. Never really looked into it further but it was a bit annoying. A few weeks later, I upgraded the machine to System 7.5.5 and everything was fine, no crashes, even with the same Adobe Photoshop 3.0.5 installation. Everything was good.

A few days ago while debugging an issue with a SuperMac video card, I downgraded the IIfx back to System 7.1.2 and the crashes came back. Within the one to three launches of Photoshop after boot, I will start seeing icon corruption in the Open Dialog and then it begins crashing subsequently. Looks like memory corruption of some kind.

I was able to reproduce easily with all extensions turned off (shift key at boot).

My usual install process for System 7.1.x is:
  • Install System 7.1.1 for IIfx (add-ins are a few printer drivers, file sharing, ethertalk, applescript, and quicktime)
  • Remove all the PowerTalk crap
  • Install System 7.1.2 and choose to update
  • Install System Update 3.0
  • Install Macintosh Drag and Drop 1.1.1
  • Install Thread Manager 2.1
  • Install Open Transport 1.3 and then update it to 1.3.1
I decided to go step by and step testing along the way to figure out whether anything I am installing is causing the issue.

First step was to install a vanilla System 7.1.1. After install, I attempted to reproduce the issue and could not after about 15 attempts. Usually the crash happens within the first 3 launches of Photoshop. I opened a bunch of memory intensive programs, also ran a benchmark test, but still could not reproduce.

Second step was to remove the PowerTalk stuff. After that, I again attempted to reproduce and could not.

Third step was to install System 7.1.2. On the first launch of Photoshop, I saw corrupted icons in the Open Dialog, and on the second launch it crashed. Hmm...

Just for good measure, I redid step 1, 2, and 3 again and again it crashed only after the upgrade to 7.1.2.

I only installed System 7.1.2 after seeing some comments about some potential bug fixes in it, even for 68K. Obviously this doesn't fully prove anything. It's quite possible my IIfx has a gremlin (hardware issue, etc) that is only being exposed by System 7.1.2 and something Photoshop is doing. But for now, I'm leaving it at System 7.1.1 with the 3.0 System Update and it's stable now.