Memory management (segmentation and paging) in 80286 and 80386: How does it work?

Posted by Andrew J. Brehm on Super User See other posts from Super User or by Andrew J. Brehm
Published on 2011-02-07T13:42:27Z Indexed on 2011/02/07 15:27 UTC
Read the original article Hit count: 250

Filed under:

memory-management

|

protected-mode

|

real-mode

I found lots of Web sites and books explaining how memory management worked on the 8086 and later x86 CPUs in Real Mode. I understand, I think, how two 16 bit values, segment address and offset are combined to get a linear 20 bit physical address (shift segment four bits to the left, add offset; segments are 64K and start every 16 bytes).

But I couldn't find any good Web sites or books that explained how memory management works in Protected Mode, specifically the differences between 80286 and 80386.

Can anyone point me to a good Web site or book (or explain it right here)?

(For extra credit, i.e. an upvote, how does it work in Long Mode?)

© Super User or respective owner

Related posts about memory-management

Memory management in objective-c

as seen on Stack Overflow - Search for 'Stack Overflow'
I have this code in one of my classes: - (void) processArray { NSMutableArray* array = [self getArray]; . . . [array release]; array = nil; } - (NSMutableArray*) getArray { //NO 1: NSMutableArray* array = [[NSMutableArray alloc]init]; //NO 2: NSMutableArray* array = [NSMutableArray… >>> More
android memory management outside heap

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi I am working on an application for android and we since we have lots of graphics, we use a lot of memory. I monitor the memory heap size and its about 3-4 Mb , and peeks of 5Mb when I do something that requires more memory (and then goes back to 3). This is not a big deal, but some other stuff… >>> More
Javascript new keyword and memory management

as seen on Stack Overflow - Search for 'Stack Overflow'
Coming from C++ it is hard grained into my mind that everytime I call new I call delete. In javascript I find myself calling new occasionally in my code but (hoping) the garbage collection functionality in the browser will take care of the mess for me. I don't like this - is there a 'delete' method… >>> More
Memory management in ObjC/iPhone

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have question in memory management (objective C). There are two ideal scenario. ============================= scenario 1 ======================================== (void) funcA { MyObj *c = [otherObj getMyObject]; [c release]; } -(MyObj *) getMyObject //(this method is available in… >>> More
Memory management / ownership question?

as seen on Stack Overflow - Search for 'Stack Overflow'
Do I have this right ... // Reactor.h @property(nonatomic, retain) NSMutableArray *reactorCore; // Reactor.m [self setReactorCore:[NSKeyedUnarchiver unarchiveObjectWithFile:[self dataFilePath]]]; ... -(void)dealloc { [reactorCore release]; [super dealloc]; } I am pretty sure I am doing… >>> More

Related posts about protected-mode

IE9 freezes with Protected Mode enabled

as seen on Super User - Search for 'Super User'
After a disk failure and a new build of Win7, IE9 locks up on most web pages including Bing. Running it as Admin works, and turning off Protected Mode also works. Neither of these was necessary prior to the rebuild and examination of colleagues' workstation config show that it's only my workstation… >>> More
How to run Firefox in Protected Mode? (i.e. at low integrity level)

as seen on Super User - Search for 'Super User'
i noticed that Firefox, unlike Chrome and Internet Explorer, doesn't run in the Low Mandatory Level (aka Protected Mode, Low Integrity) Google Chrome: Microsoft Internet Explorer: Mozilla Firefox: Following Microsoft's instructions, i can manually force Firefox into Low Integrity Mode by… >>> More
"STI", in the protected mode,CPU will restart.

as seen on Stack Overflow - Search for 'Stack Overflow'
INTEL X86 Platform. My programme run start at 2M absolute address in protected mode,everything seems ok, but when i enable interrupt with "sti", the CPU will restart. Why? is there any necessary initialization before "enbale interrupt"? i have setup the idtptr, but it seems no work. >>> More
delete a file in protected mode env(like windows xp)

as seen on Stack Overflow - Search for 'Stack Overflow'
hi I write a program to delete a file from somewhere of my harddisk in 8086 but when i use int 21h (ah=41h) an error happens and carry set to 1.and I cannot delete that. does anyone know what can I do? I think it should be from protected mode which does not allow my program to delete another file… >>> More
Memory management (segmentation and paging) in 80286 and 80386: How does it work?

as seen on Super User - Search for 'Super User'
I found lots of Web sites and books explaining how memory management worked on the 8086 and later x86 CPUs in Real Mode. I understand, I think, how two 16 bit values, segment address and offset are combined to get a linear 20 bit physical address (shift segment four bits to the left, add offset; segments… >>> More