Hi,

The processor simulator we supplied you with runs AND, OR, and XOR as
signed operations, though they should be unsigned,
as pointed out by someone on this newsgroup.

Attached is a patch that will fix this. You can either apply it
by running 'patch -p1 < Processor.PATCH' (if you are using the solaris
version of patch, you'll have to enter "machine/Processor.java" as the 
file to patch), or by just making the changes (which are trivial) by hand. 

Either way, you should definitely make the fix - the autograder
is already using it.

thanks,
rick

---------

diff -cr nachos.old/machine/Processor.java nachos/machine/Processor.java
*** nachos.old/machine/Processor.java	Mon Mar 19 22:13:01 2001
--- nachos/machine/Processor.java	Mon Mar 19 22:15:20 2001
***************
*** 1146,1154 ****
  	    new Mips(ADD,	"addiu tsi",	IFMT, DST|SRC2IMM),
  	    new Mips(SLT,	"slti tsi",	IFMT, DST|SRC2IMM),
  	    new Mips(SLT,	"sltiu tsi",	IFMT, DST|SRC2IMM|UNSIGNED),
! 	    new Mips(AND,	"andi tsi",	IFMT, DST|SRC2IMM),
! 	    new Mips(OR,	"ori tsi",	IFMT, DST|SRC2IMM),
! 	    new Mips(XOR,	"xori tsi",	IFMT, DST|SRC2IMM),
  	    new Mips(LUI,	"lui ti",	IFMT, DST|SRC2IMM|UNSIGNED),
  	    new Mips(),
  	    new Mips(),
--- 1146,1154 ----
  	    new Mips(ADD,	"addiu tsi",	IFMT, DST|SRC2IMM),
  	    new Mips(SLT,	"slti tsi",	IFMT, DST|SRC2IMM),
  	    new Mips(SLT,	"sltiu tsi",	IFMT, DST|SRC2IMM|UNSIGNED),
! 	    new Mips(AND,	"andi tsi",	IFMT, DST|SRC2IMM|UNSIGNED),
! 	    new Mips(OR,	"ori tsi",	IFMT, DST|SRC2IMM|UNSIGNED),
! 	    new Mips(XOR,	"xori tsi",	IFMT, DST|SRC2IMM|UNSIGNED),
  	    new Mips(LUI,	"lui ti",	IFMT, DST|SRC2IMM|UNSIGNED),
  	    new Mips(),
  	    new Mips(),