x86S: Intel to create 64-bit only CPUs

Retro

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Did you know that even the very latest multicore 64-bit x64 CPUs still boot up in the original 16-bit 8086 mode from 1978? They also support 32-bit modes and this is all for compatibility reasons. Well, Intel thinks it's time to finally get rid of this legacy baggage and has released a document proposing the changes for a 64-bit only future called x86S.

What I'd really like to see, is a 128-bit CPU, the next evolution. However, there's no market for them at the moment, but it would be fascinating to see one, of any architecture. It would have a huge pinout too and a smaller core count for a given process node due to the bigger size of the core.


figure-1a.png


What Would Be the Benefits of a 64-bit Mode-Only Architecture?

A 64-bit mode-only architecture removes some older appendages of the architecture, reducing the overall complexity of the software and hardware architecture. By exploring a 64-bit mode-only architecture, other changes that are aligned with modern software deployment could be made. These changes include:


Using the simplified segmentation model of 64-bit for segmentation support for 32-bit applications, matching what modern operating systems already use.
Removing ring 1 and 2 (which are unused by modern software) and obsolete segmentation features like gates.
Removing 16-bit addressing support.
Eliminating support for ring 3 I/O port accesses.
Eliminating string port I/O, which supported an obsolete CPU-driven I/O model.
Limiting local interrupt controller (APIC) use to X2APIC and remove legacy 8259 support.
Removing some unused operating system mode bits.

Full details here:

General info on 128-bit computing:
 

Geffers

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@Geffers you'll like this one.

The Raspberry Pi foundation are still supporting 32 bit for the time being although Pi devices from 2 onwards are capable of 64 bit.

The current Raspberry Pi OS is available in both 32 and 64 bit versions.

Geffers
 

Retro

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Note also the primary reason given for going from 32-bit to 64-bit is to widen the address bus. I've never understood this, since the 8-bit 6502 and Z80 CPUs from the 1970s had 16-bit address buses and worked just fine that way, so it should be the same with ARM or x86/64 CPUs.

The main benefit of wider CPU word handling is to make certain calculations faster by 2x as it handles twice as much data at once.
 
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