CHAPTER : HARDWARE & VIRTUAL MACHINES

Question 1

RISC
Reduced Instruction Set Computer

Answer 1

• makes extensive use of general purpose registers
• simplified instruction set
• fewer instructions + instruction formats
• more registers
• fixed length instructions
• less complex circuits
• more RAM use
• easier to pipeline
  eg: SunSparc

Question 2

CISC
Complex Instruction Set Computer

Answer 2

• more instructions + instruction formats
• fewer registers
• variable-length instructions
• more complex circuits
• more cache use
  eg: Intel 80486

Question 3

Interrupt

Answer 3

• signal from hardware device or software source seeking processors’s attention

Question 4

Interrupt Routine

Answer 4

• interrupt detected
• current processes paused
• moved to registers (loaded to stack)
• ISR loaded onto pipeline and executed
• paused processes resumed

Question 5

Pipelining

Answer 5

• instruction level parallelism
• execution of an instruction is split into no of stages
• when the first stage ends the first stage of next stage immediately begins
• processing of instructions is simultaneous

Question 6

Disadvantages of pipelining

Answer 6

• dependency issues can cause stalls:

Question 7

Massive Parallel Computers

Answer 7

Massive: large number of processors
Parallel: perform coordinated computation simultaneously while communicating via a messaging interface

Question 8

Hardware and Software issues when parallel processing

Answer 8

1. Hardware: - processors must be able to communicate with each other so data can be transferred
2. Software: - suitable program to allow data to be processed by multiple processors simultaneously

Question 9

SISD

Answer 9

• only one processor
• execute one instruction on one set of data
• can’t parallel process

Question 10

SIMD

Answer 10

• several ALU’s
• ALU executes same instruction using different data from a dedicated memory

Question 11

MISD

Answer 11

• each processor executes different instruction
• each processor has its own partition in a shared memory

Question 12

MIMD

Answer 12

• several processors executing instructions from a common pool
• each processor operates on different data deawn from a common pool

Question 13

Virtual Machine

Answer 13

• emulation of computer system using a system software
• use of software to implement a hardware setup

Question 14

Advantages of VM

Answer 14

• no need to buy the required hardware to test the software
• reduces setup time for test system
• can run older versions of OS

Question 15

Disadvantages of VM

Answer 15

• software emulation slower than the actual hardware
• not all hardware can be successfully emulated
• processing time can be increased as there is extra code that needs to be executed

Question 16

Difference between the Guest Operating System and the Host Operating System

Answer 16

• GOS: operating system running in a virtual machine and controls the virtual hardware
  -HOS: the operating system that controls the physical hardware
  GOS runs under the HOS

Question 17

Role of Flip Flops

Answer 17

• can store 0 or 1
• can be used to store bits of data
• memory can be create from flip flops

Question 18

Flipflop Circuit

Answer 18

• electronic circuit with 2 stable conditions using sequential circuits

Question 19

SR Flipflops

Answer 19

• 2 NAND gats
• can cause illegal states
• outputs can be used as inputs

Question 20

JK Flipflops

Answer 20

• 2 additional NAND gates
• used as extension to avoid illegal states
• all combinations are valid

Question 21

Why JK flip flops better

Answer 21

• invalid input combinations are eliminated therefore all inputs are valid
• use clock pulse for synchronization to ensure proper functioning
• increased stability