Allama Iqbal Open University Islamabad



ALLAMA IQBAL OPEN UNIVERSITY, ISLAMABAD

(Department of Computer Science)

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Course: Computer Architecture (3416) Semester: Spring, 2020

Level: Bachelor Total Marks: 100

Pass Marks: 50

ASSIGNMENT No. 1

(Units: 1–4)

Note: All questions are compulsory. Each question carries equal marks.

Q. 1 What, in general terms, is the distinction between computer organization and computer architecture? Also list and explain the key characteristics of a computer family. (20)

Q. 2 a) Draw and explain instruction cycle state diagram with interrupts. (20)

b) Consider two microprocessors having 8- and 16-bit-wide external data buses, respectively. The two processors are identical otherwise and their bus cycles take just as long.

1. Suppose all instructions and operands are two bytes long. By what factor do the maximum data transfer rates differ?

2. Repeat assuming that half of the operands and instructions are one byte long.

Q. 3 How does the principle of locality relate to the use of multiple memory levels? (20)

a) Suggest reasons why RAMs traditionally have been organized as only 1 bit per chip whereas ROMs are usually organized with multiple bits per chip.

Q. 4 Suppose that we have a multiprogrammed computer in which each job has identical characteristics. In one computation period, T, for a job, half the time is spent in I/O and the other half in processor activity. Each job runs for a total of N periods. Assume that a simple round-robin priority is used, and that I/O operations can overlap with processor operation. Define the following quantities: (20)

Turnaround time = actual time to complete a job

Throughput = average number of jobs completed per time period T

Processor utilization = percentage of time that the processor is active (not waiting)

Compute these quantities for one, two, and four simultaneous jobs, assuming that the period T is distributed in each of the following ways:

1) I/O first half, processor second half

I/O first and fourth quarters, processor second and third quarters

Q. 5 Write notes on the following topics: (20)

a) RAID levels.

b) Key services provided by an OS

ASSIGNMENT No. 2

(Units: 5–8) Total Marks: 100

Pass Marks: 50

Note: All questions are compulsory. Each question carries equal marks.

Q. 1 a) Briefly explain the following representations: sign magnitude, tows complement biased. (20)

b) Represent the following twos complement values in decimal: 1101011; 0101101.

Q. 2 What is meant by the term nesting of procedures? Also list three possible places for storing the return address for a procedure return. (20)

Q. 3 An address field in an instruction contains decimal value 14. Where is the corresponding operand located for: (20)

a) Immediate addressing?

b) Direct addressing?

c) Indirect addressing?

d) Register addressing?

e) Register indirect addressing?

Q. 4 A microprocessor is clocked at a rate of 5 GHz. (20)

a) How long is a clock cycle?

b) What is the duration of a particular type of machine instruction consisting of three clock cycles?

Q. 5 Assume that propagation delay along the bus and through the ALU of given figure are 20 and 100 ns, respectively. The time required for a register to copy data from the bus is 10 ns. What is the time that must be allowed for: (20)

a) Transferring data from one register to another.

b) Incrementing the program counter.

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