Question

2.A (25 pts) Navigating the Green Card In Figure 2.1 in our primary textbook is a table of MIPS instructions. It is a summary of the information found on the green card (the file mips_reference_data (Greeen Card).pdf in the General folder on the class drive). Focus your attention on the first page of that card and answer the following questions. Not all questions have answers, some are tricks.

a. (2 pts) What is the instruction format for “Or”? _____

b. (2 pts) What about “Or Immediate”? _____

c. (2 pts) It’s common sense that OR is going to logically look bitwise at inputs, not try and treat them as 2’s complement numbers to be added. But “Add Immediate” does treat the immediate value as a 2’s complement number. Look at the Operation equation for “OR Immediate”. What about that equation makes it obvious that the system is not treating it as a 2’s complement number? Compare it to the equation for “Add Immediate” if you don’t see the answer at first. ____________________________________________________________ __________________________

d. (2 pts) What is the instruction format for Jump and link? _______

e. (2 pts) What is the OPCODE for load Store conditional (in hex)? _______

f. (2 pts) What is the mnemonic for Load Byte Unsigned? ________

g. (4 pts) What mnemonic does an OPCODE of “01001” represent? __________ What instruction format would we use to interpret the rest of the bits? _____

h. (2 pts) If you find the value 2 in bits 0-5 of an instruction, what instruction would you assume is being run? ☐ Jump ☐ srl ☐ any I-type instruction ☐ can’t tell

i. (2 pts) What’s the opcode for the “nop” (also called “no op”) command? _______

j. (2 pts) Which commands may cause overflow exceptions (mnemonic, please)? _________________________

k. (3 pts) Here is an English-language description of what one of the commands does that can be found on the first page of the MIPS reference data sheet (I promise): Take the address of the instruction currently being run (where you yourself were found). Calculate the address of the instruction that is two instructions later and store it for safekeeping in the Return Address register. Now calculate the address of the instruction that is one instruction later than your own. Then take the high 4 bits of that address, concatenate it with bits 0-25 of your original 32-bit instruction, and add 2 zeros to the end to make it a new 32-bit address. Then change the contents of the program counter to that number. What is the name of this instruction (not the mnemonic)? __________________________________________