Talk:64-bit computing

When?

It would be good if statements like this

Currently, most proprietary x86 software is compiled into 32-bit code, with less being also 
compiled into 64-bit code (although the trend is rapidly equalizing)

were dated so the reader knows when "Currently" was.

Symbolics

I notice that there is no mention of the MIT spinoff Symbolics which was a 64 bit system.RichardBond (talk) 04:44, 22 March 2018 (UTC) RichardBond (talk) 04:44, 22 March 2018 (UTC)

Which Symbolics machines were 64-bit, and in what sense were they 64-bit? 64-bit address space? 64-bit arithmetic? ... Guy Harris (talk) 07:33, 22 March 2018 (UTC)

Linux on the timeline

I think the timeline would be better if it included a mainstream Linux distro as an example of 64-bit first appearing in OS. Ubuntu's "Wart Warthog" in 2004 had an AMD64 edition, but it's not been recommended as the primary install until 2012 ("Quantal Quetzal", 12.10); before that there were problems with things like Adobe Flash that meant Canonical recommended users to stick with a 32-bit edition. I digress. Pbhj (talk) 14:22, 19 June 2019 (UTC)

Inconsistency with use of 'Exabyte / Exbibyte' term or its equivalency

I've notice the following two sentences stating somewhat conflicting information:

1. In the introduction paragraph:

   Hence, a processor with 64-bit memory addresses can directly access 2⁶⁴ bytes (=16 exabytes) of byte-addressable memory.

2. In "Limits of processors":

   In principle, a 64-bit microprocessor can address 16 EiBs (16 × 10246 = 2⁶⁴ = 18,446,744,073,709,551,616 bytes, or about 18.4 exabytes) of memory.

Perhaps I am misunderstanding something here, but seems to me that 264 == 264, bytes are bytes, exabytes are exabytes. Same values, same units and thus the final result should have the same value if the units are same. Either both are ~18.4 Exabytes (EB), or 16 Exbibytes (EiB), something else? As the byte unit is the common ground for both Magnitude systems (1000 vs 1024), 264 == 18446744073709552000 == 16 * 10246 ≈ 18.4 × 10006 ≈ 18.4 × 1018, then the first sentence was probably meant to use exbibyte instead of exabyte. Mainly, 16 Exbibytes ≈ 18.4 Exabytes. However for consistency, the values should be changed and use the same term. Comments? Joedf (talk) 16:13, 30 October 2019 (UTC)

Not sure what WP:COMPUNITS dictates here. Guy Harris (talk) 16:57, 30 October 2019 (UTC)

Requested move 26 December 2019

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: Not moved. Others will be moved to be in line with this one.  — Amakuru (talk) 16:42, 2 January 2020 (UTC)

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64-bit computing → 64-bit – Consistent with other "n-bit" articles. WP:COMMONNAME plus WP:TITLECON outweigh WP:NOUN. (Tried to request a technical but quickly withdrawn after finding out the previous discussion.) Nemoschool (talk) 20:36, 26 December 2019 (UTC)

• Oppose "64-bit" is an adjective describing something that has 64 bits. I would support moving all the articles to "n-bit architecture", per the lede, which namedrops computer architecture._{ZXCVBNM (TALK)} 06:55, 28 December 2019 (UTC)
• Opppose – fix the other ones instead. Dicklyon (talk) 06:06, 1 January 2020 (UTC)

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The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Backwards compatibility

There seems to be an incompatibility here. On the one hand, in the section 32-bit vs. 64-bit it says 'A 64-bit processor has backward compatibility and will handle most 32-bit software', while in the timeline section it says '2019: Apple releases macOS 10.15 "Catalina", dropping support for 32-bit Intel applications'. Perhaps both are correct (I know the second one is), but some clarification (maybe in regard to what is meant by 'most') would seem to be in order. This is not a trivial matter: I've been delaying upgrading my Mac as I have some 32-bit software I want to go on being able to use. --Brian Josephson (talk) 18:12, 2 December 2020 (UTC)

A 64-bit processor with an instruction set that adds 64-bit support to an existing 32-bit instruction set, so that there's a 32-bit instruction set with which to be backward compatible, could be made capable of supporting an operating system that can run the older 32-bit code as well as 64-bit code. Most such processors are capable of that, and some of those processors are also capable of running 32-bit operating systems by running completely in 32-bit mode, but there may be some that aren't; I suspect Apple might not have bothered to provide support for 32-bit code in later A-series processors and in the M1.

An operating system running on that processor, however, might not include support for 32-bit programs. That's the case for [[iOS 11] and later releases of iOS (and thus for all releases of iPadOS, which started with iPadOS 13), and that's the case for macOS Catalina and later releases of macOS.

So there's no inconsistency (which is a better term for what you're describing than "incompatibility") in the article. The first quote describes the capabilities of some 64-bit processors (it may need to be edited to make a less definitive statement); the second quote describes what capabilities a particular version of a particular operating system offers. Guy Harris (talk) 19:09, 2 December 2020 (UTC)

Thanks for the clarification both here and on the article page. --Brian Josephson (talk) 19:54, 2 December 2020 (UTC)