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Mac IIci Error Type 7 when virtual memory is enabled

drjohnnyfever

New member
So here's an interesting problem. I've got a (as far as I can tell anyway) perfectly functional Mac IIci. It's been recapped. The logic board is clean and there was very minimal corrosion. Everything seems to be working. I've run Mac Test Pro on it. Everything checks out.

However, if I turn on virtual memory, on boot it always bombs out with "Error Type 7" (which I can't seem to find much information on.)

I've reinstalled the OS several times, on 2 different disks, and I always get the same thing. Now to be fair so far I've only tried system 7.1.1 with Update 3.0. I'll probably try 7.5.3 soon. I've also tried with different SIMMs and with the cache card removed.

Is it possible I have a bad MMU somehow? From what I understand the MMU is required to some extent for the system to work at all (non-contiguous memory). What gets me is, I think virtual memory was working in the recent past on this system.

Anyone seen anything like this before?
 

drjohnnyfever

New member
So here's an interesting problem. I've got a (as far as I can tell anyway) perfectly functional Mac IIci. It's been recapped. The logic board is clean and there was very minimal corrosion. Everything seems to be working. I've run Mac Test Pro on it. Everything checks out.

However, if I turn on virtual memory, on boot it always bombs out with "Error Type 7" (which I can't seem to find much information on.)

I've reinstalled the OS several times, on 2 different disks, and I always get the same thing. Now to be fair so far I've only tried system 7.1.1 with Update 3.0. I'll probably try 7.5.3 soon. I've also tried with different SIMMs and with the cache card removed.

Is it possible I have a bad MMU somehow? From what I understand the MMU is required to some extent for the system to work at all (non-contiguous memory). What gets me is, I think virtual memory was working in the recent past on this system.

Anyone seen anything like this before?
I can confirm I get the same behavior on a clean 7.0.1 install. Certainly seems like some kind of hardware issue.
 

cheesestraws

Well-known member
Error Type 7 is a privileged instruction being hit by the CPU when it shouldn't be. If that were going to turn up at all, it'd make sense that it would turn up in the virtual memory code. But aside from 'this error is what I'd expect from malfunctioning VM code', that doesn't help much, I'm afraid
 
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