Classnotes

Computer Systems

eXercise #4

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BITs and BYTES

Note: V=OR, &=AND, ~=NOT

1. If A=TRUE, B= TRUE and C=FALSE, evaluate the following:
   1. A & B
   2. A V C
   3. (A & ~B) V C
   4. ~(A & B) & (A & C)
   5. A & (~A V B) V (~C V ~B) & C
   
   
2. If P=10111111, Q=10101010 and R=11110000, evaluate the following:
   1. P & Q
   2. P V R
   3. (P & ~Q) V R
   4. ~(P & Q) & (P & R)
   5. P & (~P V Q) V (~R V ~Q) & R
   
   
3. Regarding the SIGNED INTEGER -9063
   1. Express it in TWO'S COMPLIMENT form
   2. Perform a SHL3 on part 1's answer, and explain the result
   3. Perform a SHR5 on part 1's answer, and explain the result
   4. What would the answer to the following sum (without converting it to binary) -9063 &~-9063
   
   
4. Regarding Software and Hardware Interrupts
   1. Wht are they PRIORITIZED prior to being noticed by the CPU?
   2. Explain the purpose of the Interupt Vector Table
   3. Describe the actions resulting from the receipt of 2 high priority interupts within a short interval of each other (supposing the interval is not sufficiently long to completely deal with the first interupt before the next, higher priority one comes along)
   
   
5. Determine the results of the following:
   1. not 255
   2. 27 or 45
   3. 255 and 3
   
   
6. Suppose we decide to encode a calendar date into BINARY using the following scheme:
   
   

           YYYYYYYMMMMDDDDD
   eg.     1100001101111101
              97   11  29  = 29th November, 1997

   1. Supposing I wished to ISOLATE just the month in a 2 BYTE WORD, what logical operations would be necessary to achieve this?
   2. What logical operations would be necessary to determine if the YEAR was 1998?
   
   

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Solutions