ELCT 707 Micro Computer Applications Final-term Exam, Winter 2009

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1 German University in Cairo Jan 16 th 2010 Information Engineering and Technology Dept. Dr. Gamal Fahmy Bar Code ELCT 707 Micro Computer Applications Final-term Exam, Winter 2009 Exam Duration: Three hours Instructions: Read Carefully Before Proceeding. 1) Calculators are allowed, but not needed. 2) Write your solutions in the space provided. If you need more space, write on the back of the sheet containing the problem. Do not put part of an answer to one problem on the back of the sheet for another problem; the pages may be separated for grading. 3) This exam booklet contains 9 pages, including this one. 4) When you are told that time is up, stop working on the test. Good Luck! Please, do not write anything below Question Total Possible Marks Final Marks

2 (5 points) 1.1 Assume that SP=FE2EH, AX=3291H, BX=F43CH, and CX=09. Find the contents of the stack and stack pointer after the execution of each of the following instructions PUSH AX PUSH BX PUSH CX (6 points) 1.2 Assume that the sound will ring by putting a value of 07 in DL for int 21 and value 02 in AH. Write a simple program to sound the bell on any press of a button unless X is pressed. If X is pressed, the program should exit. Write a program that, (a) clears the screen, and (b) sets the cursor at row=5 and column =12

3 (4 points) 1.3 Compare the number of byes of stack taken due to NEAR and FAR CALLs (5 points) List the pipelining hazards, with explanation for each of them and rank them

4 (20 points) 2. Consider a computer with the following features: 90% of all memory accesses are found in the cache (hit ratio = 0.9); The block size is 4 words and the whole block is read on any miss; The CPU sends references to the cache at the rate of 10 5 words per second; 25% of the above references are writes (writes = 25%, reads = 75%); The bus can support 10 7 words per second, read or writes (total bus bandwidth = 10 7 ); The bus reads or writes a single word at a time; Assume at any one time, 50% of the block frames in the cache have been modified; The cache uses write allocate on a write miss. You are considering adding a peripheral to the bus, and you want to know how much of the bus bandwidth is already used. Calculate the percentage of the bus bandwidth used on the average in the two cases below. This percentage is called the traffic ratio. State any further assumptions you need, if any. (a) write through (b) write back

5 3. (10 points) 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. i) Suppose all instructions and operands and instructions are two byte long. By what factor do the maximum data transfer rate differs ii) Repeat part i assuming half of the operands and instructions are one byte long and the other half is two byte long.

6 (10 points) 4.1 Show how this data will look like in memory MESSAGES DW 6667H Data db 1,2,3 Data2 dw 12,13 db 45h db 2345h (10 points) 4.2 Based on the machine code format given below Opcode D W MOD REG R/M Write the machine code for the following X86 instructions; assume Opcode for MOV, and for ADD Mov AX, BX Add CX, 1234 Mov AX,[SI] Mov DX, [BP]+1234h Add [BX],BL

7 (10 points) 5.1 A computer with 256KW of memory and 4KW of cache is organized in a set associative manner, with 4 block frames per set and 64 words per block. The cache is 10 times faster. If and we fetch some words from memory based on the following pseudo code from line 2 to line 7 What would be the speedup from Cache using FIFO. Specify the tag, the index and the offset (10 points) 5.2 Show the content of the cache before and after lines 4 and 7of the pseudo code pseudo code{ 1. fetch words from address 0 to address loop for 5 times { 3. fetch words from address 128 to address 3839 } 4. loop for 5 times { 5. Fetch words from address 0 address } 7. fetch words from address 0 to address 4351 } End of code

9 (5 points) 6.1 Define briefly what is a watch dog timer, and show the difference between a normal Watchdog and a windowed watchdog (5 points) 6.2 For the Write Back with Write Allocate policy of the memory/cache interaction Discuss briefly its scenario for reads/writes and Hits/ misses. Is it a good option, justify

Microcomputer Architecture..Second Year (Sem.2).Lecture(2) مدرس المادة : م. سندس العزاوي... قسم / الحاسبات

Microcomputer Architecture..Second Year (Sem.2).Lecture(2) مدرس المادة : م. سندس العزاوي... قسم / الحاسبات 1) Input/output In computing, input/output or I/O, is the communication between an information processing system (such as a computer) and the outside world, possibly a human or another information processing