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Groups > comp.arch.embedded > #30677
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: 64-bit embedded computing is here and now |
| Date | 2021-06-08 22:18 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <s9ojag$4ce$1@dont-email.me> (permalink) |
| References | <7eefb5db-b155-44f8-9aad-7ce25d06c602n@googlegroups.com> <87lf7kexbp.fsf@nightsong.com> <s9n10p$t4i$1@dont-email.me> <Iyz*Vc+ly@news.chiark.greenend.org.uk> |
On 08/06/2021 16:46, Theo wrote: > David Brown <david.brown@hesbynett.no> wrote: >> But for microcontrollers - which dominate embedded systems - there has >> been a lot to gain by going from 8-bit and 16-bit to 32-bit for little >> cost. There is almost nothing to gain from a move to 64-bit, but the >> cost would be a good deal higher. So it is not going to happen - at >> least not more than a very small and very gradual change. > > I think there will be divergence about what people mean by an N-bit system: There has always been different ways to measure the width of a cpu, and different people have different preferences. > > Register size Yes, that is common. > Unit of logical/arithmetical processing As is that. Sometimes the width supported by general instructions differs from the ALU width, however, resulting in classifications like 8/16-bit for the Z80 and 16/32-bit for the 68000. > Memory address/pointer size Yes, also common. > Memory bus/cache width No, that is not a common way to measure cpu "width", for many reasons. A chip is likely to have many buses outside the cpu core itself (and the cache(s) may or may not be considered part of the core). It's common to have 64-bit wide buses on 32-bit processors, it's also common to have 16-bit external databuses on a microcontroller. And the cache might be 128 bits wide. > > I think we will increasingly see parts which have different sizes on one > area but not the other. > That has always been the case. > For example, for doing some kinds of logical operations (eg crypto), having > 64-bit registers and ALU makes sense, but you might only need kilobytes of > memory so only have <32 address bits. You need quite a few KB of ram for more serious cryptography. But it sounds more like you are talking about SIMD or vector operations here, which are not considered part of the "normal" width of the cpu. Modern x86 cpus might have 512 bit SIMD registers - but they are still 64-bit processors. But you are right that you might want some parts of the system to be wider and other parts thinner. > > For something else, like a microcontroller that's hung off the side of a > bigger system (eg the MCU on a PCIe card) you might want the ability to > handle 64 bit addresses but don't need to pay the price for 64-bit > registers. > > Or you might operate with 16 or 32 bit wide external RAM chip, but your > cache could extend that to a wider word width. > > There are many permutations, and I think people will pay the cost where it > benefits them and not where it doesn't. > Agreed. > This is not a new phenomenon, of course. But for a time all these numbers > were in the range between 16 and 32 bits, which made 32 simplest all round. > Just like we previously had various 8/16 hybrids (eg 8 bit datapath, 16 bit > address) I think we're going to see more 32/64 hybrids. > 32-bit processors have often had 64-bit registers for floating point, and 64-bit operations of various sorts. It is not new.
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64-bit embedded computing is here and now James Brakefield <jim.brakefield@ieee.org> - 2021-06-07 07:47 -0700
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-07 14:13 -0700
Re: 64-bit embedded computing is here and now Paul Rubin <no.email@nospam.invalid> - 2021-06-07 22:31 -0700
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-08 07:59 +0200
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 00:39 -0700
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-08 13:04 +0200
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 17:30 -0700
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-09 09:17 +0200
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 03:12 -0700
Re: 64-bit embedded computing is here and now George Neuner <gneuner2@comcast.net> - 2021-06-12 12:58 -0400
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-12 12:40 -0700
Re: 64-bit embedded computing is here and now Paul Rubin <no.email@nospam.invalid> - 2021-06-09 09:41 -0700
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 10:12 -0700
Re: 64-bit embedded computing is here and now DJ Delorie <dj@delorie.com> - 2021-06-09 13:16 -0400
Re: 64-bit embedded computing is here and now Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2021-06-09 13:44 -0400
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 22:03 +0300
Re: 64-bit embedded computing is here and now Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2021-06-09 15:22 -0400
Re: 64-bit embedded computing is here and now Paul Rubin <no.email@nospam.invalid> - 2021-06-09 12:58 -0700
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 16:26 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 23:12 +0300
Re: 64-bit embedded computing is here and now James Brakefield <jim.brakefield@ieee.org> - 2021-06-08 12:38 -0700
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-08 22:11 +0200
Re: 64-bit embedded computing is here and now James Brakefield <jim.brakefield@ieee.org> - 2021-06-08 14:25 -0700
Re: 64-bit embedded computing is here and now George Neuner <gneuner2@comcast.net> - 2021-06-09 00:16 -0400
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-09 10:40 +0200
Re: 64-bit embedded computing is here and now Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2021-06-09 22:52 +0200
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-10 09:37 +0200
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 01:01 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 18:29 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 20:56 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 17:12 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-10 13:45 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-10 06:55 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-10 18:32 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-10 14:09 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-11 01:13 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-10 21:55 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-11 14:14 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-11 05:10 -0700
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-11 16:35 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-11 16:24 -0700
Re: 64-bit embedded computing is here and now George Neuner <gneuner2@comcast.net> - 2021-06-14 05:41 -0400
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 16:51 -0700
Re: 64-bit embedded computing is here and now Paul Rubin <no.email@nospam.invalid> - 2021-06-08 18:20 -0700
Re: 64-bit embedded computing is here and now Theo <theom+news@chiark.greenend.org.uk> - 2021-06-09 18:07 +0100
Re: 64-bit embedded computing is here and now Paul Rubin <no.email@nospam.invalid> - 2021-06-09 10:34 -0700
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 16:37 -0700
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 16:43 -0700
Re: 64-bit embedded computing is here and now Theo <theom+news@chiark.greenend.org.uk> - 2021-06-08 15:46 +0100
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-08 22:18 +0200
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-08 23:39 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 18:33 -0700
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-09 10:59 +0200
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 21:00 +0300
Re: 64-bit embedded computing is here and now David Brown <david.brown@hesbynett.no> - 2021-06-09 20:55 +0200
Re: 64-bit embedded computing is here and now Dimiter_Popoff <dp@tgi-sci.com> - 2021-06-09 22:06 +0300
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-08 16:00 -0700
Re: 64-bit embedded computing is here and now Theo <theom+news@chiark.greenend.org.uk> - 2021-06-09 13:10 +0100
Re: 64-bit embedded computing is here and now Don Y <blockedofcourse@foo.invalid> - 2021-06-09 06:19 -0700
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