15.1 Processors, Parallel processing and virtual machines

Question 1

Reduced instruction set computers (RISC)

Answer 1

is a computer with a small, highly optimized set of instructions

Question 2

Complex instruction set computers (CISC)

Answer 2

is a computer in which single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) or are capable of multi-step operations or addressing modes within single instructions.

Question 3

RISC processors

Answer 3

Reduced Instruction Set Computing

• Emphasis on software
• Executing a set of instructions only takes one cycle
• Aim is to complete cycles as fast as possible
• Simplified instructions e.g. using the MULTIPLY example, it would have to load the values to be multiplied, multiply them and then store the answer
• Longer sequences = more RAM required
• Can take advantage of pipelining
• Cheaper to produce due to needing fewer transistors
• RISC compliers are more complex as they generate extra instructions

Question 4

CISC processors

Answer 4

Complex Instruction Set Computing

• Emphasis on hardware
• Transistors store complex instructions
• Executing a set of instructions may take more than one cycle
• Aim is to complete a task in as few lines as possible
• Processor is able to understand and execute a series of operations
• Has pre-defined instructions that allow processes to be more efficient e.g. using a MULTIPLY command that knows how to take 2 numbers and multiply them together
• Short code= less RAM required

Question 5

What is interrupt handling?

Answer 5

Interrupt handling is a key function in real-time software, and comprises interrupts and their handlers. … The software assigns each interrupt to a handler in the interrupt table. An interrupt handler is just a routine containing a sequence of operations. Each of these may request input and output while running.

Question 6

Pipelining in RISC processors

Answer 6

when the processor works on different steps of the instruction at the same time, more instructions can be executed in a shorter period of time.

Question 7

Importance of registers in RISC

Answer 7

Registers act as the fast local memory store for all data processing operations.

Question 8

What are the four basic computing architectures?

Answer 8

SISD
SIMD
MISD
MIMD

Question 9

SISD

Answer 9

SISD is a computer architecture in which a single uni-core processor executes a single instruction stream, to operate on data stored in a single memory.

Question 10

SIMD

Answer 10

Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn’s taxonomy. … Such machines exploit data level parallelism, but not concurrency: there are simultaneous (parallel) computations, but each unit performs the exact same instruction at any given moment (just with different data).

Question 11

MISD

Answer 11

MISD is a type of parallel computing architecture where many functional units perform different operations on the same data

Question 12

MIMD

Answer 12

MIMD is a technique employed to achieve parallelism. Machines using MIMD have a number of processors that function asynchronously and independently. At any time, different processors may be executing different instructions on different pieces of data

Question 13

characteristics of massively parallel computers?

Answer 13

Massively parallel is the term for using a large number of computer processors to simultaneously perform a set of coordinated computations in parallel.

Question 14

What is a virtual machine?

Answer 14

In computing, a virtual machine is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination

Question 15

Benefits of virtual machines?

Answer 15

Multiple OS environments can exist simultaneously on the same machine, isolated from each other;
Virtual machine can offer an instruction set architecture that differs from real computer’s;
Easy maintenance, application provisioning, availability and convenient recovery.

Question 16

Limitations of virtual machines?

Answer 16

irtual machines are less efficient than real machines because they access the hardware indirectly. Running software on top of the host operating system means that it will have to request access to the hardware from the host. That will slow the usability.

Question 17

examples of roles of virtual machines

Answer 17

Monitoring and maintaining warehouse equipment and machinery.
Setting up manufacturing equipment.
Overseeing training of new or Junior Machine Operators.
Using machine equipment to complete tasks.
Performing routine inspections of manufacturing equipment.