Quiz submission record for quiz3-1-2 at Mon Jul  5 21:30:53 2004:

Your Answer for Question 1:
No, they cannot.  Every MIPS instruction must have its own unique bit pattern for the sole reason that if they did not, then the computer would become confused as to which instruction to execute.  This is accomplished because MIPS instructions are expressed as machine code in a total of three different formats, that all have different "flags" to differentiate them from others.  For example, an R-format instruction always has 0 as the value for its op field, which differentiates it from the I-format and J-format instructions.  To differentiate between R-format instructions, they have additional unique values for their funct field.  This similar convention is repeated with the I-format and J-format instructions.

Your Answer for Question 2:
PC-relative addressing is when the address is the sum of the PC and a constant in the instruction.  The problem is, that the instruction's address can only differ from the current address by a value of 2^16 words.  In very large programs, this can be a problem.  In our example, if the distance between Here and There is greater than 2^16 words (probably instructions, since each instruction takes 32 bits), then the assembler will be unable to specify a large enough value to add to the PC to reach the address of There.


Your unique submission ID is quiz3-1-2-cs61c-el-1089088253-1697.