Pentium

Pentium
 n.

   The name given to Intel's P5 chip, the successor to the 80486. The
   name was chosen because of difficulties Intel had in trademarking a
   number. It suggests the number five (implying 586) while (according to
   Intel) conveying a meaning of strength "like titanium". Among hackers,
   the plural is frequently `pentia'. See also {Pentagram Pro}.

   Intel did not stick to this convention when naming its P6 processor
   the Pentium Pro; many believe this is due to difficulties in selling a
   chip with "hex" or "sex" in its name. Successor chips have been called
   Pentium II, Pentium III, and Pentium IV.
    

Pentium

   <processor> {Intel}'s {superscalar} successor to the {486}.
   It has two 32-bit 486-type integer {pipelines} with dependency
   checking.  It can execute a maximum of two instructions per
   cycle.  It does pipelined {floating-point} and performs
   {branch prediction}.  It has 16 {kilobytes} of on-chip
   {cache}, a 64-bit memory interface, 8 32-bit general-purpose
   {registers} and 8 80-bit {floating-point} registers.  It is
   built from 3.1 million transistors on a 262.4 mm^2 die with
   ~2.3 million transistors in the core logic.  Its {clock rate}
   is 66MHz, heat dissipation is 16W, integer performance is 64.5
   {SPECint92}, {floating-point} performance 56.9 {SPECfp92}.

   It is called "Pentium" because it is the fifth in the 80x86
   line.  It would have been called the 80586 had a US court not
   ruled that you can't trademark a number.

   The successors are the {Pentium Pro} and {Pentium II}.

   The following Pentium variants all belong to "x86 Family 6",
   as reported by "Microsoft Windows" when identifying the CPU:

    Model  Name
    1      Pentium Pro
    2      ?
    3      Pentium II
    4      ?
    5, 6   Celeron or Pentium II
    7      Pentium III
    8      Celeron uPGA2 or Mobile Pentium III

   A floating-point division bug
   (ftp://ftp.isi.edu/pub/carlton/pentium/FAQ) was discovered in
   October 1994.

   [Internal implementation, "Microprocessor Report" newsletter,
   1993-03-29, volume 7, number 4].

   [Pentium based computers, PC Magazine, 1994-01-25].

   (2003-09-30)