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posted by takyon on Wednesday January 23 2019, @09:22PM   Printer-friendly
from the class-excavation dept.

Core blimey... When is an AMD CPU core not a CPU core? It's now up to a jury of 12 to decide

A class-action lawsuit against AMD claiming false advertising over its "eight core" FX processors has been given the go-ahead by a California judge.

US district judge Haywood Gilliam last week rejected [PDF] AMD's claim that "a significant majority" of people understood the term "core" the same way it did as "not persuasive."

What tech buyers imagine represents a core when it comes to processors would be a significant part of such a lawsuit, the judge noted, and so AMD's arguments were "premature."

The so-called "eight core" chips contain four Bulldozer modules, the lawsuit notes, and these "sub-processors" each contain a pair of instruction-executing CPU cores. So, four modules times two CPU cores equals, in AMD's mind, eight CPU cores.

And here's the sticking point: these two CPU cores, within a single Bulldozer module, share caches, frontend circuitry, and a single floating point unit (FPU). These shared resources cause bottlenecks that can slow the processor, it is claimed.

The plaintiffs, who sued back in 2015, argue that they bought a chip they thought would have eight independent processor cores – the advertising said it was the "first native 8-core desktop processor" – and paid a premium for that.


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  • (Score: 1, Informative) by Anonymous Coward on Wednesday January 23 2019, @11:40PM (2 children)

    by Anonymous Coward on Wednesday January 23 2019, @11:40PM (#790921)

    For reference, most 386 CPUs had *no* on-board cache or FPU (a.k.a math coprocessor), those were implemented in separate chips that a motherboard manufacturer could choose to include (or not). The 486 included some on-chip cache, but still mostly had no FPU (as I recall that was one of the big distinctions between the SX and DX lines in both chips). And I don't think anyone is going to argue that they were "zero-core" processors.

    It's quite a bit more complicated than that!

    Intel released the 80386 in 1985, with no FPU, and they released the (separate) 80387 FPU in 1987.

    In 1988 they released the 80386SX which had a 16-bit data bus to reduce board complexity. The normal 80387 is not compatible so they released the 80387SX to work with this variant of the processor. In an effort to reduce confusion between their product offerings, the original 80386 design (still with no FPU) is now called the 80386DX.

    Late 1989 Intel released the 80486DX. This was the first x86 offering from Intel with an integrated FPU.

    In 1991 AMD releases the Am386DX which, like the Intel 386 has no integrated FPU. At this time FPU performance mattered only for pretty niche applications and this processor ended up competing directly against Intel's early 486 offerings since (other than floating point) this still performed pretty well and was much cheaper.

    In response, and perhaps due to early production problems with the integrated FPU, Intel subsequently releases the 80486SX. This is exactly the same die as the 80486DX with the FPU present, but disabled (later respins do remove the FPU completely to save die area). It is sold at a lower cost to compete with the AMD offerings.

    Then in a bit of hilarity Intel releases the 80487SX which is also exactly the same design as the 80486DX, but an extra pin is added to the package so it does not fit in the same socket. Motherboards that accept this version work by completely disabling the "486SX" and then the "487SX" does everything. It should also be possible to remove the extra pin to fit the 487SX into the regular socket.

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  • (Score: 1) by Guppy on Thursday January 24 2019, @05:11AM

    by Guppy (3213) on Thursday January 24 2019, @05:11AM (#791062)

    Also the "486DLC" processors from Cyrix and IBM. Physically compatible with the 386DX socket (and usually drop-in compatible, but not always), it was a mix of 386 and 486 features, plus a small block of L1 cache that 386 processors lacked. And no math co-processor, but compatible with the 387DX. For a time, they offered really good price/performance value.

    There was also a 486SLC, physically compatible with the 386SX socket.

  • (Score: 0) by Anonymous Coward on Thursday January 24 2019, @07:25AM

    by Anonymous Coward on Thursday January 24 2019, @07:25AM (#791121)

    Had an Olivetti with the 486DX. Best machine I ever had. My mom threw it out... and she still denies having thrown out the Vic-20.