## Recent Question

1. How many 256*8 RAM chips are needed to provide a memory capacity of 4096 bytes? [6 marks]
a. How many bits will each address contain?
b. How many lines must go to each chip?
c. How many lines must be decoded for the chip select inputs? Specify the size of the decoder.
2. Write a program to evaluate the arithmetic statement x = (a×( b + c ) × d - e) using a stack organized computer with zero-address instructions (so only pop and push can access memory). [5 marks]
3. Consider a byte-addressable computer with 16-bit addresses, a cache capable of storing a total of 2K bytes of data, and blocks of 8 bytes. Show the format (include field names and sizes) of a 16-bit memory address for: [8 marks]
a. direct mapped
b. fully associative
c. 4-way set associative
d. Where (which block or set) in cache would the memory address BAD016 be mapped for each of three mapping techniques above? You can specify the answer in decimal if you wish.
4. More registers appears to be a good thing, in terms of reducing the total number of memory accesses a program might require. Using the arithmetic expression S = (A+B)-(C+D), support this statement. [Hints: First, determine the number of memory accesses necessary using MARIE and the two registers for holding memory data values (AC and MBR). Then perform the same arithmetic computation for a processor that has more than three registers (for example, R1, R2, R3, R4) to hold memory data values.] [4 marks]
5. Suppose a process page table contains the entries shown below. Using the format shown in Table, indicate where the process pages are located in memory. [3 marks]
Page
Frame
Valid Bit
0
--
0
1
3
1
2
--
0
3
--
0
4
2
1
5
0
1
6
--
0
7
1
1
7. Suppose a disk drive has the following characteristics: [4 marks]
6 surfaces
953 tracks per surface
256 sectors per track
512 bytes/sector
Tract-to-track seek time of 6.5 milliseconds
Rotational speed of 5,400 RPM.
a. What is the capacity of the drive?
b. What is the access time?
8. Suppose you have the instruction “Add 800”. The memory contents are given below, and the contents of AC and the base register are 200 and 100 respectively.
800 900
900 1000
1000 500
1100 600
1200 800
1300 250
What would be loaded into the AC if the addressing mode for the operand is: [6 marks]
a. immediate
b. direct
c. indirect
d. indexed
1. Explain why modern machines consist of multiple levels of virtual machines. Why not just have two levels, the digital logic level and the high-language programming level? [4 marks]
2. Given a (very) tiny computer that has a word size of 6 bits, what are the smallest negative numbers and the largest positive numbers that this computer can represent in each of the following representations? [6 marks]

a. Signed magnitude
b. One's complement
c. Two's complement

3. Convert the followings: [4 marks]

a. AC1216 to binary
b. -10710 to 8-bit 2’s Complement
d. 100111102 (8-bit 2’s complement representation) to decimal

4. A Computer uses IEEE-754 format to represent floating points. What value ( in decimal) the computer represents if the floating point is represented using the following binary digits: [4 marks]
11000001010100000000000000000000

5. Charles Sturt University (CSU) academic director want to hire a lecture in Sydney Study Center. The applicant has worked in three universities before; University of New South Wales (UNSW), Macquarie University, and Sydney University. Before he will hire him, he must get input from these three universities. After few weeks of receiving feedback from all three, he has come to the following conclusions:

· Hire if two of them say yes and one says no.
· Hire if all of them say yes.
· Don't hire otherwise.

Construct a truth table and find the minimized Boolean function to implement the logic telling the director when to hire. Draw a circuit diagram for the Boolean function. [6 marks]

6. Complete the truth table for the following sequential circuit: [6 marks]