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Three concurrent processes X, Y, and Z execute three different code segments that access and update certain shared variables. Process X executes the P operation (i.e., wait) on semaphores a, b and c; process Y executes the P operation on semaphores b, c and d; process Z executes the P operation on semaphores c, d, and a before entering the respective code segments. After completing the execution of its code segment, each process invokes the V operation (i.e., signal) on its three semaphores. All semaphores are binary semaphores initialized to one. Which one of the following represents a deadlock-free order of invoking the P operations by the processes?
The following program consists of 3 concurrent processes and 3 binary semaphores. The semaphores are initialized as S0=1, S1=0, S2=0. Process P0 Process P1 Process P2 While (true) { Wait (S0); Print ‘0’ Release (S1); Release (S2); } Wait (S1); Release (S0); Wait (S2); Release (S0);   How many times will process P0 print ‘0’? 
Which of the following statements are CORRECT? 1) Static allocation of all data areas by a compiler makes it impossible to implement recursion. 2) Automatic garbage collection is essential to implement recursion 3) Dynamic allocation of activation records is essential to implement recursion 4) Both heap and stack are essential to implement recursion
In the bounded buffer problem, there are the empty and full semaphores that ____________
Based on the paragraph given below answer the following question: The traditional methods of combinational circuits involve simplification and realization using gates. Using these methods, complex functions have been integrated and are easily available in IC form. There is an attractive array of devices like a multiplexer, demultiplexer, decoders, comparators, parity generators/checkers, which significantly reduce IC package count there by reducing the system cost. The system design is greatly simplified because the laborious and time-consuming simplification methods are generally not required with these devices. This also improves the reliability of the system by reducing the number of external wired connections. But they have some limitations as well. Different memories like ROM, PROM can also be used to implement combinational circuits without much simplification.   A ROM is to be used to implement a “Squarer”, which outputs the square of a 3-bit number. What must be the size of the ROM?
Each of a set of n processes executes the following code using two semaphores a and b initialized to 1 and 0, respectively. Assume that count is a shared variable initialized to 0 and not used in CODE SECTION P. CODE SECTION P wait (a); count=count+1 ; if (count==n) signal (b) ; signal (a) ; wait (b) ; signal (b) ; CODE SECTION Q What does the code achieve?
A certain computation generates two arrays a and b such that a[i]=f(i) for 0 ≤ i < n and b[i] = g (a[i] ) for 0 ≤ i < n. Suppose this computation is decomposed into two concurrent processes X and Y such that X computes the array a and Y computes the array b. The processes employ two binary semaphores R and S, both initialized to zero. The array a is shared by the two processes. The structures of the processes are shown below. Process X: private i; for (i=0; i
Consider the following solution to the producer-consumer synchronization problem. The shared buffer size is ?. Three semaphores empty, full and mutex are defined with respective initial values of 0, ? and 1. Semaphore empty denotes the number of available slots in the buffer, for the consumer to read from. Semaphore denotes the number of available slots in the buffer, for the producer to write to. The placeholder variables, denoted by P, Q, R, and S, in the code below can be assigned either empty or full. The valid semaphore operations are: wait ( ) and signal ( ). Producer: Consumer: do {         wait (P) ;         wait (mutex) ;         //Add item to buffer         signal (mutex) ;         signal (Q) ; } while (1) ; do {          wait (R) ;          wait (mutex) ;          //Consume item from buffer          signal (mutex) ;          signal (S) ; } while (1) ;   Which one of the following assignments to P, Q, R and S will yield the correct solution?
Consider the following threads, T1, T2, and T3 executing on a single processor, synchronized using three binary semaphore variables, S1, S2, and S3, operated upon using standard wait() and signal(). The threads can be context switched in any order and at any time. T1 T2 T3 While(true) { Wait(S3); Print(“C”); Signal (S2); } While(true) { Wait(S1); Print(“B”); Signal (S3); } While(true) { Wait(S2); Print(“A”); Signal (S1); }   Which initialization of the semaphores would print the sequence BCABCABCA….?
Consider the procedure below for the Producer-Consumer problem which uses semaphores: semaphore n = 0; semaphore s = 1;   void producer() { while(true) { produce(); semWait(s); addToBuffer(); semSignal(s); semSignal(n); } }         void consumer() {            while(true)            {             semWait(s);             semWait(n);             removeFromBuffer();             semSignal(s);              consume();              } }   Which one of the following is TRUE?