Author Topic: Why do classic Mac OS's crash/freeze so much?  (Read 364 times)

Offline Syntho

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Why do classic Mac OS's crash/freeze so much?
« on: November 26, 2018, 05:09:22 PM »
I don't have a specific problem right now, but I'm interested to hear about why OS9 and below was always so prone to crashing. More than the type 1 2 and 3 errors, I get freezing. I'm talking like, you move the mouse, and it freezes! Just random, nonsensical freezing. Yes, just from moving the mouse! Or you try to copy a file, or click on another finder window you've got open, or just anything. I can better understand the errors we get when using programs that aren't so stable, or if there's some conflict or whatever, but this random freezing just makes no sense. I currently don't experience it too often, but when it happens, it comes seemingly out of nowhere. It reminds me of Windows Millennium. XP and OSX were a lot more stable than any classic Mac OS I've ever used.

Can anyone explain why this happens?

Offline IIO

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #1 on: November 26, 2018, 05:52:14 PM »
if it happens without a previous error warning therhe is something wrong with your system or hardware, because OS9 normally does not do this.

but after an error it wil happen sooner or later, so you should reboot right after errors, especially hardware related stuff like error 2, 3, 11 ... later you will forget that you had errors before and might loose some work.
"It is true that the "pre-emptive multitasking" advantage present in OS X can be illustrated by downloading CD-ROM ISOs and rendering chaos theory formulas while simultaneously instant messaging and posting on FaceBook what you ate... but in reality, what did you create?"
- DieHard, random forum troll at macos9lives.com

Offline Syntho

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #2 on: November 26, 2018, 07:40:32 PM »
So basically all of my hardware has issues? I've encountered it enough on OS8.6 across all of my systems that I think this is just an idiosyncrasy of the OS. I've had it happen on OS9 before as well. I wonder what's causing it.

Offline FdB

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #3 on: November 26, 2018, 09:39:11 PM »
Maybe common knowledge… or standard practice, but “trimming the fat” or “paring down” what apps, CPs or extensions (that you don’t really need) is optimal for stability on any “workstation” regardless of OS version or its’ intended duty. No internet, mail, music, games, etcetera on my graphics workstations. And I do mean completely stripped down except for their intended specific use.

The “division of labor” ‘round here is placed on 3 different "older" Macs. One is a scan & Photoshop station (OS 8.6). Another is for 3-D modeling & rendering (OS 9.2.2), while a third (OS 9.2.2 & 10.4.6) Mac is dedicated to Illustrator and the merging of images (and text) for final output. And all three are tied together over a LAN (each workstation has dual monitors for tool palettes, etc.).

A  friend of mine (DAW) operates in a similar fashion, only sharing between just two Macs. One for the raw sound files and “preliminary work” and a second Mac for additional “polish” (strings and other  effects) before tweaks & final output or archiving… with back-ups written along the way as he progresses towards his finished piece. Again, with no unnecessary or extraneous un-needed “fat”.

I use a much newer iMac for email & internet and “sneaker-net” to move files for upload or download. Here, trimmed down to the absolute bare necessities after many years, only the “internet portal” machine freezes, crashes or pukes around here anymore, thankfully.

Please excuse my blabbering-on here if you’re already geared in this manner… some may not be aware of this “eliminate-the-variables” approach. Consider this, then… for them.

I never liked those… turntable-tape deck-CD player-tuner combo stereos either. ;)
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Offline GaryN

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #4 on: November 26, 2018, 09:47:52 PM »
I've excerpted this from Wikipedia "Cooperative Multitasking":

Early multitasking systems used applications that voluntarily ceded time to one another. This approach, which was eventually supported by many computer operating systems, is known today as cooperative multitasking. Although it is now rarely used in larger systems except for specific applications, cooperative multitasking was once the only scheduling scheme employed by Microsoft Windows and Classic Mac OS to enable multiple applications to run simultaneously.

As a cooperatively multitasked system relies on each process regularly giving up time to other processes on the system, one poorly designed program can consume all of the CPU time for itself, either by performing extensive calculations or by busy waiting; both would cause the whole system to hang.


Although "one poorly designed program consuming all of the CPU time for itself" is a common cause of "freezes" it's not the only cause. In the old Mac OS, memory allocation was fixed (by the settings in the "get Info" window) and it's easy to have an app simply run out of memory, thereby causing it to hang and therby causing the entire system to go belly-up. All of this is why Apple went through the incredibly awkward and painful process of moving the entire Mac ecosystem to the preemptive multitasking UNIX-based system called OSX.

Actually, considering the fragility of the entire principle the old Mac OS is based on, it's kind of amazing that it does work as well as it does. You do need to keep some guardrails in place to help ensure that however. The most important one is probably keeping unnecessary memory usage to an absolute minimum. Having multiple apps open in the background - even if they're idle, is the #1 no-no. The system cannot reallocate idle memory to active processes as needed the way it can in OSX, so the best-running systems are usually doing one thing at a time. This is not the place for an entire primer on how to manage Mac OS memory but it's a fine art that every Mac OS user should be familiar with.

If your computer is "freezing" at random it's probably not really random - you just haven't identified the common cause of it yet.
Does the Command-period combo ever help? That's tool #1 for systems stuck from "busy waiting".
There's also a fine line with PT "piles of PCI cards" systems where Doofusdesign wants more memory than it should be entitled to, that may require some trial-and-error experimentation to find the sweet spot where all processes have just enough RAM in their pocket. That varies with each user since it depends RAM available, exactly which apps you use, etc.

Let me take a second to poke you again by reminding you that that is one of the main things Apple tried to address as well as possible with each succeeding release.

OS9 has better memory allocations than OS8 and many processes have better cooperative decision-making.

Yeah, it also has a lot of what you may see as unnecessary junk and clutter too, but that doesn't matter if you simply don't use it. Excess extensions and such can't be an issue if they're simply not enabled. I think you already have a clue about this since you're suddenly asking a lot of questions about memory allocation, defragging and such.

Anyway, as usual, I'm just sayin'…



Offline Syntho

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #5 on: November 26, 2018, 09:52:46 PM »
Command-period. Never head of it. I'll keep that in mind.

Offline FdB

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #6 on: November 26, 2018, 10:43:54 PM »
Command-period = stop / quit.

And yes, one can allocate more memory to chosen applications under OS 8.6 as needed…
while keeping others relegated to their bare stated minimums… as less-needed. ;)
« Last Edit: November 26, 2018, 11:13:57 PM by FdB »
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Offline OS923

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #7 on: November 28, 2018, 05:42:31 AM »
Command-period is meant to stop programs that are still processing events (and then they need to have code to reply to this particular key event). If you want to stop a program that doesn't process events, for example because it got into an infinite loop, then you have to use option-command-escape. If it goes really wrong, for example because a pointer traveled outside a buffer and you try to write at a wrong address, then it freezes and you have to restart.

Offline Naiw

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #8 on: December 06, 2018, 03:51:29 PM »
The answer to the topic is simple- it basically lacks any of the protective mechanisms implemented in modern operating systems to keep the OS stable. For classic Mac OS to be stable, responsive etc every single piece of code must be have correctly- if they don't you freeze or in best case scenario get an OS error dialog. This could be caused by either software or hardware- but modern machines that behaves very unstable it's almost certainly an underlying hardware issue, on old macs it's almost certainly always a software issue.

Offline ELN

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Re: Why do classic Mac OS's crash/freeze so much?
« Reply #9 on: December 06, 2018, 05:45:24 PM »
Attempts at error recovery were often futile, too. Because a crashing application could leave all sorts of global memory (or even hardware) in an inconsistent state, “unexpectedly quit” messages tended to recommend saving your work and restarting.