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Intel's 15 Most Unforgettable x86 CPUs

Intel Pentium: A Bothersome Bug

The Pentium, introduced in 1993, was interesting for more than one reason. It was the first x86 to drop the traditional model number for a more attractive name, since Intel wasn’t allowed to trademark a name made up of numbers only. It’s also famous because of a bug it contained. On the first generations of Pentiums, certain division operations produced an incorrect result. Intel replaced the processors, but the damage was done. A very rare error gave rise to the first big IT media buzz.

The Pentium was sold in three different versions, the first without a CPU multiplier, the second with a multiplier (including the very familiar Pentium 166), and the last with the SIMD instruction set for x86s, MMX. The Pentium MMX also increased the size of the Level 1 cache and brought in a few minor improvements. This was the first Intel x86 capable of executing two instructions in parallel. The L2 cache was on the motherboard with these processors (running at the frequency of the FSB).

Code nameP5, P54P55 (Pentium MMX)
Date released19931997
Architecture32 bits32 bits
Data bus64 bits64 bits
Address bus32 bits32 bits
Maximum memory4096 MB4096 MB
L1 cache8 KB + 8 KB16 KB + 16 KB
L2 cacheMotherboard (FSB frequency)Motherboard (FSB frequency)
Clock frequency60-200 MHz133-300 MHz
FSB50-66 MHz60-66 MHz
FPUon chipon chip
SIMDnoMMX
Fabrication process800-600-350 nm350 nm
Number of transistors3.1-3.3 million4.5 million
Power consumption8-16 W4-17 W
Voltage5 V-3.3 V2.8 V
Die surface area294-163-90 mm²141 mm²
ConnectorSocket 4, 5 or 7Socket 7

Here’s a little explanation of the Pentium bug: certain calculations using the FPU resulted in erroneous results. This was fairly rare—though sources disagree about exactly how rare—and Intel replaced the defective processors free of charge. Here’s an example of a Pentium error:

4195835.0/3145727.0 = 1.333 820 449 136 241 002 (correct result) 4195835.0/3145727.0 = 1.333 739 068 902 037 589 (incorrect result on a defective Pentium)

  • Arkz
    great article with only a few slight errors (like saying the core2duo has 1-4 cores... i don't think there's a 1 cored version lol)

    Looking forward to the AMD article.
    Reply
  • aleluja
    To correct you. Core 2 Duo has ONLY 2 cores, not more, not less.
    Core 2 Quad, has 4 cores and Core Solo has 1 core.
    Reply
  • @Arkz

    Yes there is a singal core,

    http://en.wikipedia.org/wiki/List_of_Intel_Core_2_microprocessors#Single-Core_Mobile_processors
    Ok it is not under the same branding but it is part of the same microarchitecture
    Reply
  • Yuka
    I might be wrong, but i resemble that the Pentium 166 (32bits adress bus and all) had support for 4Gb of memory. I remember IBM sold it's top line (at that time) with 64Mb support (even with SDR PC100/66 support). Correct me if i'm wrong please.
    Reply
  • neiroatopelcc
    The core 2 does supply 1-4 cores - 2 cores per die, where one might be disabled, and one or two dies on a socket. It's no less right to call a core2duo a cpu with 1-4 cores, than it is to put the pentium d on the same page as a single core prescot, as it's the very same principle.
    Reply
  • cangelini
    Arkzgreat article with only a few slight errors (like saying the core2duo has 1-4 cores http://en.wikipedia.org/wiki/Coree ... i don't think there's a 1 cored version lol)Looking forward to the AMD article.
    Thanks for the heads-up! I tweaked that passage to better represent the Core 2 architecture's available configurations!
    Reply
  • randomizer
    vosesterOk it is not under the same branding but it is part of the same microarchitecture Exactly. The article says:

    ArticleThere are many versions of the architecture, resulting in configurations with a different number of cores
    There is no mention of the branding, so there is no actual error there, just misinterpretation.
    Reply
  • ImSpartacus
    Arkzgreat article with only a few slight errors (like saying the core2duo has 1-4 cores... i don't think there's a 1 cored version lol)Looking forward to the AMD article.
    http://www.newegg.com/Product/Product.aspx?Item=N82E16819116039
    Yes, it isn't called a "Core 2 Duo," but it uses the Core architecture and only has a single core enabled.

    But I will have to say, there aren't any 3 core models...
    Reply
  • magicandy
    Good to hear you're not only doing an AMD article, but an ATI one as well (in response to the Nvidia article you did earlier, assuming). A sign of class from the new Tom's is a welcome one.
    Reply
  • harrycat88
    I wish they would get rid of those stupid SNAP Linkbubless and Inteltex misguiding links. Who ever invented those stupid annoying double lined text popups should have been burned at the stake
    Reply