128 bits is 64 bits too many

Did you hear the joke about the 128 bit processor? Let me offer some factual corrections to an article which appeared a couple of days ago in the Korea Herald and which has fueled speculation…

This is an incredibly exciting time for the ARM ecosystem, with leading solutions from ARM partners taking computing to the next level.  Over the past month, beginning at the ARM TechCon event in Santa Clara and continuing worldwide at our ARM Technical Symposia, we have publicly presented the future of ARM technologies to over 7000 engineers and counting.  Those engineers have seen the facts:

  • ARM leads the way with our 32-bit CPUs supporting a range of power and performance points, including solutions using our big.LITTLE technology.  These will be in about 10 billion chips sold in 2013 and will continue to grow for a very long time into the future.
  • ARM has launched a family of ARMv8-A architecture based processors that support 64-bit, and the first products based on these chips are coming to market.
  • In the coming year I expect we will see increasing announcements of 64-bit solutions across mobile, networking and server markets.

News reports have suggested that ARM is developing 128-bit processor technology: this is not true.  64-bit processors are capable of supporting the needs of the computing industry now and for many years to come. There are absolutely no plans underway for 128 bit ARM-based chips because they simply aren’t needed. Rumors to the contrary are simply incorrect.

Furthermore, comments attributed to any ARM executive including my colleague Antonio Viana that allegedly discuss any specific partner’s chip plans for the future or 128 bit development are inaccurate: no such comments have been made.

The ARM partnership is built around diversity of solutions, and ARM works diligently to assure our partners can announce their products at a time of their choosing, and showing their unique technical differentiation and value add.  As a result, we absolutely do not disclose our partners product plans but defer to partners to make their own statements.  The result is a vibrant marketplace of innovative solutions that serve a range of end application needs, which I find incredibly exciting.

  • Here's a review paper that (partly?) captures the current interest in higher-than-double precision arithmetic.


    I spoke with Bailey recently and he was saying it'd be great to see h/w support for double double in HPC

  • The current NEON can already achieve128 bits registers by viewing as 16 registers. But double the number of 128 bits registers in next generation neon would be an attractive idea :)

  • Yes, at present it would probably be silly to have an 128-bit address path. Perhaps it would also be silly to have a 128-bit data path.

    But I think having 128-bit registers for data processing (integer and float) might be interesting, though.

    I believe that a 64/128-bit processor might be the next thing we'll see. Perhaps the register width will be increased further - maybe to 256 bits, before we even see a 128-bit data- or address-path.

    One might (over-)simplify the meaning of the three:

    • Registers: Speed of internal calculations. (I think this is the first thing we'll see)
    • Data-path: Speed of storage. (Probably the next thing after registers)
    • Address-path: Size of storage. (We'll probably not see this right away)