1.1 Systems Architecture

Question 1

What is the purpose of the processor(CPU)?

Answer 1

• Retrieves Data/Instructions from Main Memory (fetch)
• It processes data(decodes instructions)
• Carries out instructions(executes them)
• Stores data into main memory once executed

Question 2

What are the three busses between the cpu and ram?

Answer 2

• Address bus
• Control bus
• Data

Question 3

PC

Answer 3

Program counter

Question 4

MAR

Answer 4

Memory Address Register

Question 5

MDR

Answer 5

Memory Data Register

Question 6

ACC

Answer 6

Accumulator

-results of calculations from the ALU are stored in the ACC

Question 7

ALU

Answer 7

Arithmetic Logic Unit

-performs arithmetic and logical operations including +,-,AND,OR

Question 8

CU

Answer 8

Control Unit

Question 9

Memory stored on the CPU?

Answer 9

Cache

Question 10

RAM

Answer 10

Random Access Memory

Question 11

CIR

Answer 11

Current Instruction Register

Question 12

What the fetch part of fetch decode execute?

Answer 12

1) Copy address from PC to MAR
2) Get data from RAM and copy to the MDR
3) Copy from MDR to CIR
4) Increment PC

Question 13

What the decode part of fetch decode execute?

Answer 13

1) Split opcode from data address in MDR

2) Control unit interprets opcode

Question 14

What the execute part of fetch decode execute?

Answer 14

1) Data address copied from PC to MAR
2) Get data from RAM and Copy to MDR
3) Instruction executed

Question 15

What are features of RAM?

Answer 15

• Holds data and instructions that are currently in use by the processor
• Located on the motherboard
• Directly Accessible by the processor
• All data/instructions are lost once power is turned off

Question 16

ROM

Answer 16

Read Only Memory

Question 17

What is the ROM?

Answer 17

• instructions are permanently etched onto a ROM chip
• when power is turned off instructions still remain on the ROM chip
• bootstrap loader is held on ROM(it gives the instruction to start up the operating system

Question 18

EEPROM, examples and function

Answer 18

Electronically Erasable Programmable Read Only Memory
E.g. SIM cards, flash memory
-instructions/data can be erased electronically and replaced

Question 19

What is a bus?

Answer 19

A bus is a set of parallel wires connecting two or more independent components of a computer system in order to pass signals between them

Question 20

What does the address bus do?

Answer 20

• carries addresses from the processor to main memory or other I/O devices
• It’s one direction
• the processor generates an address
• all data/ instructions are returned on the data bus

Question 21

What does the data bus do?

Answer 21

• carries data from main memory(or secondary storage devices) to the processor
• bi-directional
• data can be read/written

Question 22

What does the control bus do?

Answer 22

-control signals instruct which data will be traveling to/from memory

Question 23

How does clock speed affect the CPUs performance?

Answer 23

-Processors have a clock speed measured in Hz(cycles per second)
-a 1G Hz Processor executes 1 billion instructions per second
The quicker the clock speed the more instructions per second the processor can do

Question 24

How does the number of cores affect the performance of a CPU?

Answer 24

Processors can be multi core
Each core executes instruction independently
Dual core may execute up to twice as many instructions per second

Question 25

How does the number of cache affect the performance of a CPU?

Answer 25

Cache is very fast usually small amount of memory stored on the processor chip
Increasing the cache size will reduce the number of memory to disc transfers and thus may speed up processing of these instructions

Question 26

Define embedded systems:

And what are some examples?

Answer 26

A computer system built into another device.

E.g. Car engines, washing machines, dish washer, microwave

Question 27

What is the Von Neumann architecture?

Answer 27

The collection of registers in the CPU which uses the fetch decode execute cycle