计算机组成与结构-习题.pdfVIP

1． Immediately after the CPU executes an instruction that is neither a branch nor a jump instruction, the program counter (a) remains unchanged (b) is incremented to point to the following instruction (c) is incremented by one (d) has a value that cannot be determined without further information 2 ． The program counter contains (a) the number of times a program has been executed (b) the address of the CPU instruction that is about to be executed (c) the amount of memory a program is currently using (d) the number of CPU instructions a program has executed so far 3 ． In one computer, the bytes with addresses A, A+1, A+2 and A+3 contain the integer 256, and the variable declared with int * a; has the value A. In a different computer, the bytes with addresses B, B+1, B+2 and B+3 also contain the integer 256, and the variable declared with int * b has the value B. Which of the following are necessarily true? I ． The contents of A+1 are equal to the contents of B+1. II ．The contents of A+1 are equal to the contents of B+2. III ．*a == *b (a) I only (b) III only (c) II and III only (d) I and III only 4 ． A jump instruction (a) changes the program counter only if its operand is equal to zero (b) changes a pointer to point to the next element of an array (c) increases the program counter (d) unconditionally sets the program counter to its operand 5 ． A branch instruction (a) sets the program counter to one of many possible values (b) unconditionally sets the program counter to its operand (c) sets the program counter to one of two possible values (d) increases the program counter by a fixed amount 6 ． A CPU register is a word of CPU memory that (a) records the results of periodic CPU diagnostics (b) is automatically loaded when a CPU instruction refers to a word of normal memory (c) houses a critical variable for the duration of the execution of a program (d) is ex