Execute Cycle

1. What are the main functions of the CPU?

2. Explain what the CPU should do when an interrupt occurs. Include in your

answer the method the CPU uses to detect an interrupt, how it is handled, and what

happens when the interrupt has been serviced.

3. Suppose we have 4 memory modules and each module has 8 addresses. Draw

the memory modules with the addresses they contain using:a) High-order Interleaving

and b) Low-order interleaving.

4. Memory organization

a) Suppose that a 32MB system memory is built from 32 1MB RAM chips.

How many address lines are needed to select one of the memory chips?

b) Suppose a system has a byte-addressable memory size of 4GB. How many

bits are required for each address?

c) Suppose that a system uses 16-bit memory words and its memory built

from 32 1M × 8 RAM chips. How large, in words, is the memory on this system?

d) Suppose that a system uses 32-bit memory words and its memory is built

from 16 1M × 8 RAM chips. How many address bits are required to uniquely identify

each memory word?

e) Suppose we have a 1024-word memory that is 16-way low-order

interleaved. What is the size of the memory address offset field?

5. Suppose that a 2M x 16 main memory is built using 256K

×

8 RAM chips

and memory is word-addressable.

a) How many RAM chips are necessary?

b) If we were accessing one full word, how many chips would be involved?

c) How many address bits are needed for each RAM chip?

d) How many banks will this memory have?

e) How many address bits are needed for all of memory?

f)

If high-order interleaving is used, where would address 14 (which is E in hex) be

located?

g) Repeat Exercise f) for low-order interleaving.

6. Explain the steps of the fetch-decode-execute cycle. Your explanation should

include what is happening in the various registers.