Chapter 11 QA

11. Instructions Sets: Addressing Modes and Formats True or False: 1. T/F – Operand data can be represented in any order in an instruction. ANS : F 2. T/F – Addressing modes define whether operand values are reside in registers or in memory. ANS : T 3. T/F – The type of addressing mode in the current instruction is found during execution stage. ANS : F 4. T/F – Indexing is a type of displacement addressing. ANS : T 5. T/F – Incrementing or decrementing index registers take one extra clock cycle. ANS : F 6. T/F – In certain addressing modes, there are special bits allocated to indicate floating point/integer registers. ANS : T 7. T/F – In the x86 architecture, all addressing modes that involve memory access need to specify the base address and displacement value. ANS : T 8. T/F – Branch instruction also follow register indirect type of addressing. ANS : F 9. T/F – Different branch types follow different addressing modes. ANS : F 10. T/F – Instruction lengths can be of any arbitrary size. ANS : T

11. T/F – The number of inputs to the ALU unit plays a vital role in deciding the instruction format. ANS : T 12. T/F – The PDP-11 was primarily used for a 8bit machine. ANS : F 13. T/F – VAX type instructions can include up to 6 operands. ANS : T 14. T/F – The ARM Thumb instruction format encodes the 32-bit instruction into 16-bits. ANS : T 15. T/F – Assembly language programming uses hexadecimal representation. ANS : T 16. T/F – I/O and system commands can be run using assembly language. ANS : T

Multiple Choice Questions: 1. While deciding the proper addressing mode, the trade-off is between operand address range and A. ALU size B. Number Registers C. Flexibility D. None of the above ANS : C 2. The ALU or shifter is used to find the exact location of one of the operands in A. Immediate addressing B. Register Indirect addressing C. Displacement addressing D. None of the above ANS : C 3. The main advantages of register addressing mode are A. Flexibility and Speed B. Speed and number of address bits C. Address bits D. All of the above ANS : D

4. This concept is used while implementing instructions in relative addressing mode A. Register reuse B. Temporal locality C. Spatial locality D. None of the above ANS : C 5. What type of programs can be implemented using indexing addressing mode? A. Recursive B. Convolution C. All of the above D. Loops ANS : C 6. Post and pre-indexing are done for instructions of indexing and what other addressing mode? A. Immediate B. Register C. Displacement D. Indirect ANS : D 7. Transfer-of-control type instructions typically use what type of addressing mode? A. Immediate B. Register indirect C. Relative D. None of the above ANS : A 8. Load/store type instruction use A. Indirect B. Immediate C. Relative D. All of the above ANS : A 9. The instruction length has to be a multiple of A. Integer array B. Character length C. Page size D. None of the above ANS : B 10. x86 instructions have a prefix to indicate control over shared memory A. Load prefix B. Lock prefix C. Dirty data prefix D. Coherency prefix ANS : B 11. The PDP-8 microinstructions are used for A. Immediate addressing B. Register reference addressing C. Memory reference D. None of the above ANS : B

12. Direct addressing is used in A. Memory referencing B. PDP-8 C. PDP-10 D. PDP-11 ANS : C 13. This instruction format does not have a fixed instruction length A. VAX B. PDP -10 C. PDP-11 D. PDP-8 ANS : C 14. In the VAX instruction format, the opcode is of A. 8 bytes B. 2 bytes C. 1 byte D. None of the above ANS : B 15. ARM instruction have an opcode length of A. 8 bytes B. 0.5 bytes C. 1 byte D. None of the above ANS : A 16. How is the decision to use thumb or 32 bit instruction decided in an ARM core? A. Program counter B. Return address register C. Processor control register D. All of the above ANS : A Fill up the blanks: 1. _______________ define the order in which the operands of an instruction are represented. ANS : Addressing mode 2. In a system without ________________ the ____________ will be in registers or the main memory. ANS : Virtual memory, effective address 3. ____________ is the most simplest form of addressing involving least register reads. ANS : Register addressing 4. Segmented memories are typically accessed using _____________ addressing

modes. ANS : Displacement 5. _________________ addressing mode has little/no memory reference but is still scarcely used because of its low _______________. ANS : Register , address space 6. _____________ addressing mode is similar to the register indirect addressing mode. ANS : Indirect addressing 7. The number address bits decides the ____________ that can be referenced. ANS : Address range 8. ________________ addressing is a general purpose addressing mode that can save address space. ANS : Direct 9. The _________________ is a general purpose register. ANS : Accumulator 10. ________________ decides the segment to be used by the instruction. ANS : Opcode 11. The __________ instruction format has special purpose stack pointer register. ANS : Stack 12. ______________ means the addressing mode does not depend on the operands used. ANS : Orthogonality 13. The ARM instruction formats are all of the same length of ____________. ANS : 32bits 14. ____________immediate constants are expanded to 32bits in the ARM instruction set. ANS : 8bit 15. ______________ is the communication means used by the machine to send data and control signals.

ANS : Machine language 16. The _________________ is used convert the above into assembly language. ANS : Assembler