Fetch execute cycle
Download
1 / 14

Fetch-Execute cycle - PowerPoint PPT Presentation


  • 85 Views
  • Uploaded on

Fetch-Execute cycle. Memory Read operation. Read from memory. PC. Main Memory. 1. MAR. Address bus. Other registers. Data bus. MDR. Control bus. ALU. Control Unit. Clock pulses. The Program Counter (PC) holds the address of the next instruction. Electronic Clock. PC. Main

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Fetch-Execute cycle' - aira


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Memory read operation

Memory Read operation

Read from memory


PC

Main

Memory

1

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

The Program Counter (PC) holds the address of the next instruction

Electronic

Clock


PC

Main

Memory

10110111

1

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

The contents of the PC are copied to the Memory Address Register (MAR)

Electronic

Clock


PC

Main

Memory

1

MAR

Address bus

Other

registers

10110111

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

Memory address to be accessed is placed onto the address bus

Electronic

Clock


PC

Main

Memory

1

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

>>read>>

Clock pulses

Electronic

Clock

The control bus sends a read signal


PC

Main

Memory

01010111

1

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

The contents of the memory location are passed along the data bus to the Memory Data Register (MDR)

Clock pulses

Electronic

Clock


PC

Main

Memory

2

1

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

The PC is incremented ready for the next instruction

Electronic

Clock


Memory write operation

Memory Write operation

Write to memory


PC

Main

Memory

2

MAR

Address bus

Other

registers

Data bus

MDR

1110011

Control bus

ALU

Control

Unit

Clock pulses

Electronic

Clock

Data is placed onto the data bus


PC

Main

Memory

2

MAR

Address bus

Other

registers

11110010

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

Memory address to be written to is placed onto the address bus

Electronic

Clock


PC

Main

Memory

2

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

>>write>>

Clock pulses

Electronic

Clock

A ‘write’ signal is sent along the control bus


PC

Main

Memory

2

MAR

Address bus

Other

registers

Data bus

MDR

10111110

Control bus

ALU

Control

Unit

Clock pulses

Electronic

Clock

The data is transferred to the destination in memory


PC

Main

Memory

3

2

MAR

Address bus

Other

registers

Data bus

MDR

Control bus

ALU

Control

Unit

Clock pulses

Electronic

Clock

The PC is incremented


ad