I upgraded my Macintosh II to a Macintosh IIfx by purchasing the Macintosh
IIfx logic board upgrade and two 4MB Macintosh IIfx memory upgrades.
This is actually the second logic board that I've ordered. The first was
returned to Apple because it had the multichime error sound when first
turned on with the full 8MB of RAM. However, it worked properly with only
4MB installed.
The second logic board has a similar problem. If 8MB of RAM is installed,
the unit acts strangely. Here are some symptoms:
* The desktop is extremely slow to update at startup,
particularly when it tries to read the hard drive.
* When an icon is moved, multiple remnants of the icon are left behind
on the desktop.
* Inserting a locked, known good floppy disk into the drive causes a
dialog "Disk is damaged and can't be used". Reinserting the same disk
into a Macintosh IIci or Macintosh SE results in normal response.
* The system has trouble launching programs and eventually crashes
with a system error = 03 or 10 error.
* Disks that were not write-protected were permanently damaged and
could not be repaired with Norton Utilities for the Mac. When opened
on any other system, the disk would indicate that it had used space,
but no icons appeared.
* Disks inserted would often be missing several icons. When those
same disks are inserted into other systems or this system running
4MB, all icons appear.
The interesting thing is that if the machine is reduced to 4MB of RAM
populated in bank A, it works just fine. It doesn't matter which RAM
chips are placed in Bank A -- as long as Bank B is empty, the system is
normal.
We have heard of this problem before. It turned out to be bad RAM causing
the crashes and erratic behavior. Replace the memory in the back bank
with four new SIMMs of a different brand.