Talk:Real mode

Exactly one megabyte?

As far as I know there might be 64kByte-16 Bytes more: If the address line A20 is activated the addresses 0xffff:0x0001 - 0xffff:0xffff are beyound the 1MByte-Limit. There have been DOS drivers that only contained relative jumps (and therefore could start at a address that doesn't read0xXXXX:0x0000) and so could be placed somewhere in this memory range. Peterpall (talk) 19:11, 22 January 2015 (UTC)

Speculation

This is probably the reason why until Windows ME it was possible to restart the computer to MS DOS mode from within the operating system.

Windows ME is no different from the 9X lineage WRT to protection levels so this statement is nothing more than speculation and requires references to back up this assertion. 75.203.60.249 (talk) 08:47, 10 September 2012 (UTC)

This statement is mainly nonsense. Rebooting to DOS mode has nothing to to with switching modes while running. --Ikar.us (talk) 22:47, 23 April 2013 (UTC)

Ring Levels

A description of ring levels would also be nice. For example: ring 0

There are no ring levels in real mode. Everything runs with unlimited privileges.EvilKeyboardCat (talk) 08:47, 27 April 2013 (UTC)

Lamen info

'''''WHAT IS THIS IN LAMENS TERMS'''''

---

It is very difficult to explain CPU operating modes without assuming a basic level of understanding on the part of the reader. If you don't have that understanding, following some of the related links in the article will help.

BTW, it's "Laymen's Terms."

Is celeron good for Africa

Hi,
found out that the Celeron PROCESSOR Generates more hot than the other INTER PROCESSORS,
 I feel Celeron should not be used in some parts of Africa,e.g,West,North,Southern Africa

skygold

^That is a good question, as long as your computer has proper functioning fans and heatsink the temperature shouldn't adversly affect the operation of your computer anywhere on earth people can live.^

Article contradicts itself

The first sentence states that real mode is a mode of 80286 and later processors, but the righthand sidebar/inset states that real mode was first supported in the 8086. -86.134.90.115 19:42, 11 August 2007 (UTC)

I've just noticed the same point. —Preceding unsigned comment added by 81.56.41.149 (talk) 23:26, 13 September 2008 (UTC)

It was not a mode in the oldest processors, because there were no other modes. --Ikar.us (talk) 22:47, 23 April 2013 (UTC)

Textbook

Was the article text here copy/pasted from a textbook, or something? It's full of "Figure 1", "Figure 2" (but doesn't actually have any figures), and ends with "In the next chapter...". It should probably be rewritten to have a more encyclopedic style, and someone should probably check if this is a copyvio... Phlip (talk) 10:40, 28 December 2008 (UTC)

Hmm, it really seems to come from this page http://www.internals.com/articles/protmode/realmode.htm 62.177.69.197 (talk) 22:16, 28 December 2008 (UTC)

Switching to real mode

The section describes purely 80286 issues, and I don't think there even was DPMI for 286? For 386, it is possible to switch back to realmode in a 'normal' way, not resetting the CPU, and DOS extenders commonly used the virtual 8086 mode instead of switching back. Someone should revise the section to include all this. Jalwikip (talk) 12:48, 10 June 2009 (UTC)

Real mode or supervisor mode or what.

Ring (computer security) refers to supervisor mode and seems to describe real mode. The difference should be explained or the articles should be merged. Rsduhamel (talk) 22:38, 23 July 2009 (UTC)

Is here somebody confused by the characteristic "unlimited access" in both cases? Needs more understanding of the concepts. --Ikar.us (talk) 22:47, 23 April 2013 (UTC)

Megabytes or Mebibytes

The article header states that "Real mode is characterized by a 20 bit segmented memory address space (giving exactly 1 MiB of addressable memory)..." However the link on MiB links to the Megabyte article. I'm guessing that's a boo-boo. 203.206.78.138 (talk) 10:22, 30 October 2011 (UTC)

In the real mode we becomes exactly 1 MiB + (64 KiB - 1 Byte) of addressable memory. Dirk — Preceding unsigned comment added by 85.177.153.121 (talk) 08:09, 13 February 2014 (UTC)

Fixed contridictions

Hey Guys,

I've put this on the talk page in case anyone would like to dispute it.

As it says on the x86 modes table beside the text, the 80286 was not the first processor to use real mode. Saying that it was is like saying that capitalism started in the cold war, while the term may have originated there it was only because there was now an alternative and a new word was needed to differentiate it. Real mode has been around since the first x86 processors but back then it was just "normal mode" because there was nothing else. I've changed a few things to "all x86 CPUs" because they all support it. While the architecture may not have been as advanced in the 80186 or 8086, it was very similar as the core features (or lack thereof) were the same. EvilKeyboardCat (talk) 13:47, 21 November 2012 (UTC)

All x86 CPUs start in real mode when reset?

Stated in the intro, but it's not really covered in the body. Is it still true? See:

64-bit machines have new EFI firmwares. These don't load a bootstrap program from sector #0 of a disc at all. They bootstrap by the EFI Boot Manager loading and running an EFI boot loader application. Such programs are run in protected mode. This is the EFI bootstrap process. Snori (talk) 21:58, 9 May 2017 (UTC)

"80286 computes effective addresses to 24 bits even in real mode" claim needs clarification

"Addressing capacity" section contains the following sentence: "However, the 80286 has 24 address bits and computes effective addresses to 24 bits even in real mode". While accessing 24th address line (A23, 0-indexed) is technically possible for 80286 in real mode by means of changing internal segment descriptor value (thus entering what is informally known as "unreal mode" or "flat mode"), it obviously is not possible in "pure" real mode. Depending on which interpretation the author had in mind (computing addresses exclusively in "pure" real mode or including "unreal mode"), the sentence in question is either wrong (because the claim is false for "pure" real mode) or confusing (as the claim makes no reference to "unreal mode" and thus contradicts what the rest of the article states about real mode addressing rules and capabilities). Either way I think the sentence in question, as it currently stands, requires clarification. Hopefully, someone more qualified than me may wish to elaborate on it. 37.128.124.190 (talk) 09:24, 10 February 2023 (UTC)