[comp.sys.mac.programmer] System 6.0.x won't run MultiFinder with Mr. Bus Error on a Plus.

earleh@eleazar.dartmouth.edu (Earle R. Horton) (08/12/89)

     I've tried this on two Mac Plus machines, one mine and one
Dartmouth's.  Get the file "INIT Mr. Bus Error" from "Phil and Dave's
Excellent CD" and drop it into the system folder along with the System
6.0.x stuff (I've tried 6.0.1, 2, and 3 so far).  Boot a Plus from the
disk and you'll get an address error every time you try to start up
MultiFinder.

     Mr. Bus Error is an INIT specially designed for programmers.  It
helps to detect use of nil Handles by installing a VBL task that puts
a bad value in location zero, and keeps putting it there.  The value
is 0x0F0F0F01, I think.  Anyway, the instruction the 68000 stops on is 
"move.l d2,$xxxx(a0)" and sure enough, a0 has the bogus address in it
when the crash occurs.  It's quite an alarming crash if you don't have
a debugger installed.

     I tried this on several systems that were strictly vanilla,
except for the addition of Mr. Bus Error and a debugger into the
system folder.

Earle R. Horton