: Everytime I hit f10 to step through it gives me the following in the
: messages window:
:         "Exception occured at PC=0x00000000
:             Bad address in text read:  0x00000000"
: help !!!

The solution to the above problem is something that many of you may be
interested in:   if you ever run a program when the PC is zero, then you
will get the above error message which is caused by one of 2 USER errors:

1) The COMMON occurrence of this user error occurs after you have a run 
   a program once already and you want to re-run it by stepping...

   Once you run a program (using go, step, or continue), the done
   pseudo-instruction (li $v0, 10 followed by syscall) will set the PC to 0.  

   Then if you press f10 one more time, you'll get the above error.

   SOLUTION:
     *reload the program first  (Simulator --> Reload <your file> 
     *THEN it is ok to step using the f10 key.

2) The second user error occurs when first executing a program as follows:
   (this shouldn't happen once you get PCSPIM installed correctly)

   if when you run pcspim, open an input file, and the message 
   window tells you that it assembled correctly, 
   then if you step and it tells you that the PC = 0, that means
   that you don't have the OSroutine called trap.handler loaded by the
   simulator, i.e. your simulator settings are set wrong.  (Other symptoms
   would have been:  the symbol table tells you start is undefined, and
   the text segment window shows that YOUR program is starting at 400000)

   SOLUTION: 
     *look in the simulator menu, select settings, 
     *put a checkmark in the box:
		load trap file
     *and insert the trap file name:  (using either browse or type)
		C:\Program Files\PCSpim\trap.handler
     *"ok" will cause the file to be set, and you can now continue, only
      if you exit PCSPIM and restart it.