Serial vs parallel computing

Question 1

What is a serial computation?

Answer 1

• A problem is broken into a secrete series of instructions
• Instructions are executed sequentially one after another
• Executed on a single processor
• Only one instruction may execute at any moment in time

Question 2

What is parallel computing?

Answer 2

In the simplest sense, parallel computing is the simultaneous use of multiple computer resources to solve a computational problem.

Question 3

Step-by-step parallel computing is:

Answer 3

1. The problem is broken down into discrete parts that can be solved simultaneously.
2. Each part will need to have a series of instructions to execute the sub problem.
3. These instructions are executed simultaneously on the different processors
4. Need overall control mechanism

Question 4

What should the computational problem be able to do?

Answer 4

• Be broken apart into discrete pieces of work that can be soled simultaneously;
• Execute multiple program instructions at any moment in time;
• Be solved in less time with multiple compute resources than with a single computer resource

Question 5

The computer resources are typically:

Answer 5

• A single computer with multiple processors/ cores
  OR
• An arbitrary number of such computer connected by a network

Question 6

Parallel computing has been considered to be “the high end of computing”, and has been used to model difficult problems in many areas of science and engineering.

Describe an example where parallel computing is used

Answer 6

MRI scan - data from body is split into discrete parts or sub problems. Each part is processed to generate images for each section with its own instructions by multiple processors.
The results of the images from each section are put together to render a full body image.

Question 7

Two unrelated terms used in computing are
- parallel transmission of data
- parallel processing
Explain what each means and give an example of where parallel processing might be useful

Answer 7

• Parallel transmission of data: can send multiple bits simultaneously over multiple lines/ wires.
• Parallel processing: simultaneous use of multiple cores to perform one task. Example: producing image of MRI scan.

Question 8

Just because it is a parallel processor doesn’t mean it is working in parallel. Explain comparing multi core and a single core processor:

Answer 8

• Multi core processor: multiple cores running in parallel on a single device.
• Single core processor:

Question 9

Just because the processing of the jobs happens in parallel doesn’t mean it is faster. Explain:

Answer 9

-

Question 10

Describe the purpose of a register in the CPU

Answer 10

is temporary storage for data or instructions that is located on the processor.

Question 11

Describe the purpose of Control Unit

Answer 11

Manages execution of instruction and synchronises instruction.

Question 12

Describe the purpose of the ALU

Answer 12

Forms functions of input values and produces a single output result.

Question 13

Name three registers that are essential to the fetch-execute cycle

Answer 13

• Memory address register
• Memory data register (instruction that needs to be executed from memory)
• Current instruction register

Question 14

Briefly describe the fetch-decode-execute cycle

Answer 14

FETCH- Program counter: stores address of the next instruction to be executed
FETCH - MAR: address of next instruction copied to MAR increment PC to address of next instruction
FETCH- Address bus: carries address to memory instruction at address is copied to MBR via data bus instruction in MBR is copied to CIR.

op-code is going to decode and the operand goes to ALU which carries out calculation to the ACC.

Question 15

Describe using example what the difference between a general purpose register and a dedicated register.

Answer 15

Dedicated register - specific purpose and cannot be changed by programmer.
General purpose register - can be changed by programmer/ can store data.