Quiz submission record for quiz6-2-2 at Thu Jul 29 10:04:57 2004:

Your Answer for Question 1:
THe EPC holds the address of the affected instruction, used to handle exceptions.  Cause is a register used to record the cause of the exception.  A MIPs instruction that could access this is add.  It would cause an arithmetic overflow, which is an exception type, with cause =1.

Your Answer for Question 2:
An imprecise exception is an exception caused during an out of order completion of instructions during pipelining.  

Your Answer for Question 3:
Polling, which is like having the system monitor the status of the mouse by reading signals from it, has a drawback of wasting a lot of proccessor time.  With polling, a device simply puts the information into a status register.  But the processor never knows when the I/O has completed an operation, and must continually check the register.  Thus the system is dramatically slowed down, because the processor is just so much faster than I/O device.

Your Answer for Question 4:
Memory mapped means that each register appears as a special memory location.  A program usually controls four memory-mapped device registers.  

la $t0,ffff0000; //address of receiver control
la $t1,ffff0004; //address of receiver data
loop:
beq $t0,$0,loop;
lw $v0,0($t1);
b loop;


Your unique submission ID is quiz6-2-2-cs61c-av-1091120697-1071.