Discussion in "Project Help" started by    erez44    Mar 28, 2013.
Thu Mar 28 2013, 10:06 PM
#1
hello i want to understand how the memory is organize i know that i have rom and ram.
but inside ram i have data memory and idata memory what is the difference are they the same memory?
Fri Mar 29 2013, 06:23 AM
#2
in 8051 you only have data memory no idata as it only have 128 bytes of ram. Whereas if you go for 8052 architecture where you have 256 bytes or ram. lower 128 bytes are data and upper 128 bytes are idata.

Now the name data and idata differs in the way you can address them. idata can only be addressed indirectly i.e. using r0, r1 registers are pointers. e.g.
mov r0, #81h ;load r0 with 81h memory location
mov a, @r0 ;read 81H location


whereas data location can be accessed directly/indirectly i.e. method shown above and direct method e.g.
mov a, 7fH


The reason idata can only be addressed indirectly, coz they overlap the SFR memory area. so if you access upper 128 bytes directly you read SFR region whereas if you read them indirectly you read idata region. Usually when writing assembly programs, idata is used for stack and lookup tables etc.

Hope this has helped you understanding difference in both memories If you have any question do post again.
Tags 8051 memory organization8051 idata and data memory differencekeil idata region8051 idata memory
Fri Mar 29 2013, 05:09 PM
#3
thanks mister i appreciate your answer do you know where i find material to read about it?
Sat Mar 30 2013, 10:03 PM
#4
Just Google
memory organization 8051
Tue Apr 02 2013, 11:02 AM
#5
or just read MCS51/8051 user manual. Download it from here:
http://www.8051projects.net/download-c16-8051-ebooks-tutorials.html

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Thu Nov 21 2019, 12:30 PM
raj2555
how to interface 8051 microcontroller with NRF24L01+ module
ExperimenterUK
Sat Oct 12 2019, 10:23 PM
Log in.. then post your code in the 8051 forum
Sat Oct 12 2019, 10:18 AM
Bhadra Sajikumar
i am doing a countdown timer with 8051 for my project, unfortunately our professor had to take a leave of absence before he could teach us most of it.. can someone explain the .asm code of it for me?
Mon Sep 23 2019, 07:37 AM
Nathaniel
I am doing a project for my schools wireless security system with cameras,sensors and spot lights using 8051 micro controller, could you help me out with the design and its source code.
Wed Sep 18 2019, 08:48 PM
Caryn Kover
Thank you for your time,
ExperimenterUK
Mon Aug 05 2019, 07:09 PM
@Ismail ..post in forum, give details
Mon Aug 05 2019, 04:33 PM
Ismail balghmi
Hello. Please I won't download
ExperimenterUK
Wed Jul 24 2019, 12:47 AM
@BUSTER123 Please post in the forum
Tue Jul 23 2019, 06:13 PM
BUSTER123
hello! newbie here. i am kind of a guy who hates using ready - made existing libraries, so this helped a lot as i was trying to control and write to a character lcd display. however, i can't figure out how to set the cursor position. for example, i want to set it to the 5th column in the first row, so position 5. so according to the table, i am sending 10000101 on the 8 data lines of the lcd (register select pulled low). the cursor does not move there however. and i cant move the cursor left or right too. is it something wrong that i am doing? thank you.
ExperimenterUK
Thu Jul 11 2019, 07:55 PM
@ramos https://www.theengineeringprojects.com/2017/09/l298-motor-driver-library-proteus.html

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