Quiz submission record for quiz6-2-2 at Wed Jul 28 22:47:51 2004:

Your Answer for Question 1:
The EPC register holds the address of the address that causes an exception, while the cause register records why the exception was caused.  They are part of the coprocessor 0 registes.  To move them into registers, the command is mfco (dest) $13 for the cause register, and mfco (dest) $14 for the EPC register.

Your Answer for Question 2:
An imprecise exception is the practice of not always associating the correct instruction with the exception.  This is a problem of pipelines because the exception may not be detected until the second or third stage.  Machines that use imprecise exception may just set the EPC to be the current PC, and allow the exception handling hardware to figure out the problem.

Your Answer for Question 3:
The principal drawback of polling is that system resources have to be continually utilized to check for input from the user.  For something like the mouse, polling may be a good idea because we have no idea when the user is going to use the mouse.  But for something like disk reads, etc, it is not useful to have polling because they could potentially require a lot of bandwidth, and we are not receiving input continually.

Your Answer for Question 4:
It means that what you type into the SPIM terminal is recorded as input to memory, and that output from memory will be displayed on the terminal.

lui $t0, 0xffff
lui $t1, 0xffff
ori $t1, $t1, 0x0004

loop: lw $t2, 0($t0)
      andi, $t2, $t2, 1
      beq $t2, $0, loop
      lbu $v0, 3($t1)


Your unique submission ID is quiz6-2-2-cs61c-el-1091080071-1898.