8
for class on
Wednesday
Oct. 13, 2010
Please read sections 4.1, 4.2, and 4.3 of the Patterson & Hennessy text.
Please turn in written responses to these questions:
1. What changes (if any) to the datapath (the black lines) of Figure 4.11 would you need to enable it to execute the MIPS addi instruction? You may include a photocopy of the figure with your changes if you wish.
2. Compared with the control for the plain add instruction, what (if any) changes to the control (the blue wires) of Figure 4.11 would you need to enable it to execute the MIPS addi instruction? You don't need to say which control bits should be 0's or 1's. Just say what (if anything) would need to be different from the control settings for add, including any necessary additional control wires. (You may want to peek into section 4.4 of the text.)
Then, be prepared to discuss the following in class:
3. We will put together a simple MIPS processor datapath (somewhat like the EDSAC datapath of the very first class) and then run some instructions through it to see how it really works. Please think about how the different instruction types--arithmetic, loads, stores, branches--use different parts of the datapath, and how these quite different instructions use the datapath in very similar ways.
4. What about floating-point? Floating-point instructions come out of the instruction memory like any other instructions--where should the floating-point hardware be, and how should it be hooked up with the integer datapath? How would a floating-point load instruction work?