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Heman Apr 16, 2000 03:43 AM
system error - "Bus error"??
today, when I was working with AppleWork 5.04 and IE5 on my iMac/dvse.
A bomb comes up sudenly saying that there is a system error and it is called "BUS ERROR" then the iMac hang. I have no chioce but the reset button and I lost 5 pages of work. Can anyone tell me what is bus error? and what can be done?
seanscottusa Apr 17, 2000 10:22 AM
A bus error is an internal hardware error. It occurs on the system bus (which runs between CPU and memory, video, etc.). Sometimes one may just get a random bus error, which is no big deal outside of possible loss of work. However, if you are getting bus errors often, then you may have a major problem with your logic board (like overheating). If you are getting this error often you may want to reinstall system software. If that does not solve the problem, I would take it to an Apple certified technician.

Hope this helps,
GORDYmac Apr 17, 2000 10:43 AM
A bus error can be anything, merely a communication breakdown between two components. It can be USB, Firewire, or any of the hundreds of busses inside your machine.

Frustrating, huh.
farmerDave Apr 17, 2000 11:26 AM
I just got through resolving a similar problem on a friends g4, although the bus error was happening early in the boot process just before extensions started loading. the computer booted ok from the system cd, so I did a clean system re-install. End of problem. Moral: do not assume hardware in the event of a bus error.


cujo Apr 17, 2000 11:57 AM
It is probably a fluke, but if it keeps it up, I know that I have this problem on alot with Microsoft products, but not to badly with IE5. I have found that is is usually currupt microsoft software, and or prefs. Just to check it out, take all of the explorer prefs out of the preferences folder, and then run Microsoft Internet First Run. If that solves your problem slowly inter grate all of the preference files back into the system folder.
P Apr 17, 2000 07:51 PM
Sad to disagree with you all, but if the Mac is complaining about a "bus error", it's not detecting what you are talking about. I'm not saying you're wrong - if the main system bus had failed, then that would be a bus error, but the Mac would have no way of detecting that.

No, "bus error" - or error type 1, which is the same thing - is a sort of memory protection fault. When the weak memory protection of the MacOS detects that something is wrong with how a program is using memory, it gives error type 1 or type 2 - that last is an address error, btw.

Error type 1 means that the logical memory address used by the program is illegal because it is either:

* Out of the logical memory range, ie address ing byte number 200,000,000 when there are only 100,000,000 (or approx 100 megs) of logical, or virtual, memory.

* In a forbidden part of the logical memory, such as address 0 or a forbiden part of the system heap.

What can you do about it? Increase the memory partition, most importantly. Try removing some extensions as well.

Her's a little more detail:

It's a bit outdated, though. Their description is pretty much my first point above, but the other is also true nowadays.
Orbit Apr 18, 2000 06:35 PM
Yeah, pretty much right- a bus error ususally occurs when a program writes to a nil pointer (ie. address 0) and overwrites the low memory system globals. This is a Very Bad Thing™ and if it doesn't cause the system to crash immediately, it'll do it soon enough.

A type 2 error, or address error, is more related to processor registers and how they relate to memory... the processor can read variables into its registers by putting two words, or 16-bit binary numbers, into one 32-bit register, or by putting one long word, or 32-bit binary number into the register. A word can be read in at an even or odd address, but long words can only be used at even addresses. This error could be an error in the program, but it's sometimes indicative of random code being thrown at the processor, so I it sometimes rears its ugly head in data/disk corruption situations. This is all in the linked TIL article above, and some of it is paraphrased. Thank you, Apple TIL!!
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