Quiz submission record for quiz3-1-2 at Sun Jul  4 18:58:55 2004:

Your Answer for Question 1:
No, if the two MIPS instructions were different, then they could have similar bit patterns but never the same. MIPS instructions come in two different formats: R-type, normally used for arithmetic instructions, and I-type, normally used for data transfers. All instructions are 32 bits and contain various fields that instruct what type of operation is being done, source registers, destination registers, etc. The I-type format allows for a 16-bit address, which allows operations to be done on more complicated data structures like arrays, etc. Therefore, every field is unique in its purpose and will carry different bit patterns.  

Your Answer for Question 2:
The assembler might have problems with this expression mainly because it assumes that conditional branches will branch to a nearby instruction. Under PC-relative addressing, the program counter (PC) contains the address of the current instruction, allowing branching only within +/- 2^15 words of the current instruction when using the PC as the register to be added to the address. Hence, if the “there:” label was more than 2^15 lines away, the assembler would not be able to store the address of where to go next in it’s 16-bit address field (since PC-relative addressing uses I-format instructions for branches). The 16-bit address field cannot store an address of a program bigger than 2^16. 


Your unique submission ID is quiz3-1-2-cs61c-ei-1088992735-2795.