[Computer Composition Principles] Exercises (1) - Instruction System

4. The functions of program control instructions are ().
A. Carry out arithmetic and logic operations
B. Carry out data transfer between main memory and CPU
C. Carry out data transfer between CPU and I/O devices
D. Change program order of execution

4.D
Program control instructions are used to change the sequence of program execution, and enable the program to have the ability of testing, analysis, judgment and cyclic execution.

5. Which of the following instructions is not a program control instruction ().
A. Unconditional transfer instruction
B. Conditional transfer instruction
c. Interrupt implicit instruction
D. Loop instruction

5.c
Program control instructions mainly include unconditional transfer, conditional transfer, subroutine call and return instructions, loop instruction interrupt implicit instruction is realized by hardware, not an instruction that exists in the instruction system, and it is even less likely to belong to the program control category instruction

7. In the stack computer, the address of the operand is not given in the instruction format of some arithmetic instructions with the zero address of the stack, and the
two operands involved come from ( ).
A. accumulator and register
B. accumulator and scratchpad
C. The top and sub-stack units of the stack
D. The top unit and scratchpad of the stack

7.c
Operation instructions with zero address are also called stack operation instructions, and the two operands involved come from the stack top and the sub-stack top unit.
Note: The number of memory accesses for stack instructions depends on whether a soft stack or a hard stack is used. If it is a soft stack (the stack area
is realized by if it is hard memory), then it needs to access the memory 4 times for the binocular operation: fetch the index, fetch the source number 1, fetch the source number 2, store the result. Stack (the stack area is realized
by the register), then Memory needs to be accessed only once when an instruction is fetched.

9. It is a single-address instruction that can complete the arithmetic operation of two numbers. The address code specifies one operand, and the other operand comes from the
() method.
A. Immediate addressing
B. Implicit addressing
C. Indirect addressing
D. Base addressing

9. There is only one address code in the B
single address instruction. When completing the arithmetic operation of two operands, one operand is pointed out by the address code, and the other operand is usually stored in the accumulation register (ACC), which belongs to implicit addressing.

13. A computer system uses 32-bit single-word instructions, and the address code is 12 bits. If 250 two-address instructions are defined
, there can also be () single-address instructions.
A. 4K
B.8K
c.16K
D.24K

14. [2017 Unified Exam Questions] A computer is addressed by byte, the instruction word length is fixed and there are only two instruction formats, including 29 three-address instructions and 107 second-address instructions. Each address field is 6 bits, so the instruction word The length should be at least ().
A. 24 bits
B. 26 bits
c. 28 bits
D. 32 bits

13.
The D address code is 12 bits, the operation code length of the two-address instruction is 32-12-12=8 bits, 250 two-address instructions have been defined, 28-250=6, that is, the single-address instruction 6× can be designed 212 =24K items.
14.
There are 29 A three-address instructions, so its opcode is at least 5 bits. Calculated with 5 bits, it leaves 32-29=3 kinds of operation codes for the second address. And the second address has another 6 bits for the operation code, so the maximum number is 3*64 = 192. Therefore, the instruction word length should be at least 23 bits, because the computer is addressing by byte, which needs to be a multiple of 8, so the instruction word length should be at least 24 bits, choose A.