274
Why we don't have 128-bit CPUs (www.xda-developers.com)
submitted 6 days ago by jwr1@kbin.earth to c/technology@lemmy.world
you are viewing a single comment's thread
view the rest of the comments
[-] wewbull@feddit.uk 142 points 5 days ago* (last edited 5 days ago)

We do, depending on how you count it.

There's two major widths in a processor. The data register width and the address bus width, but even that is not the whole story. If you go back to a processor like the 68000, the classic 16-bit processor, it has:

  • 32-bit data registers
  • 16- bit ALU
  • 16-bit data bus
  • 32-bit address registers
  • 24-bit address bus

Some people called it a 16/32 bit processor, but really it was the 16-bit ALU that classified it as 16-bits.

If you look at a Zen 4 core it has:

  • 64-bit data registers
  • 512-bit AVX data registers
  • 6 x 64-bit integer ALUs
  • 4 x 256-bit AVX ALUs
  • 2 x 128-bit data bus to DDR5 (dual edge 64-bit)
  • ~40-bits of addressable physical RAM

So, what do you want to call this processor?

64-bit (integer width), 128-bit (physical data bus width), 256-bit (widest ALU) or 512-bit (widest register width)? Do you want to multiply those numbers up by the number of ALUs in a core? ...by the number of cores on a piece of silicon?

Me, I'd say Zen4 was a 256-bit core, but you could argue any of the above numbers.

Basically, it's a measurement that lost all meaning so people stopped using it.

[-] CetaceanNeeded@lemmy.world 7 points 5 days ago

Not to mention most "8-bit" CPUs had a 16 bit address bus.

[-] wewbull@feddit.uk 7 points 4 days ago

Yes, because 256 memory locations is a bit limiting.

load more comments (18 replies)
this post was submitted on 23 Jun 2024
274 points (94.5% liked)

Technology

55562 readers
3854 users here now

This is a most excellent place for technology news and articles.


Our Rules


  1. Follow the lemmy.world rules.
  2. Only tech related content.
  3. Be excellent to each another!
  4. Mod approved content bots can post up to 10 articles per day.
  5. Threads asking for personal tech support may be deleted.
  6. Politics threads may be removed.
  7. No memes allowed as posts, OK to post as comments.
  8. Only approved bots from the list below, to ask if your bot can be added please contact us.
  9. Check for duplicates before posting, duplicates may be removed

Approved Bots


founded 1 year ago
MODERATORS