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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 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].


A family of 32 and 64-bit x86-based CPU chips from Intel. The term may refer to the chip or to a PC that uses it. During their reign, Pentium chips were the most widely used CPUs in the world for general-purpose computing. Although superseded by the Core line in 2006 (see Intel Core), various Pentium 4 models are used in entry-level PCs and other devices.

The first Pentium chip was introduced in 1993 as the successor to the 486; thus the Pentium began as the fifth generation of the Intel x86 architecture (see x86). The Pentium uses a 64-bit internal bus compared to 32-bits in its 486 predecessor. Following is a brief summary of Pentium models:

Pentium 4 Dual Cores - Introduced in 2005
The Pentium D and Pentium Processor Extreme Edition were the first dual-core Pentium chips from Intel. Although both chips included Intel's 64-bit EM64T technology (later named "Intel 64"), the Pentium D did not include Hyper-Threading, but the Extreme Edition did. See Pentium Processor Extreme Edition.

Pentium 4 - Introduced in 2000 (1.4-3.4 GHz)
Latest Pentium architecture started out with a 400 MHz system bus and 256KB L2 cache (later increased to 800 MHz and 2MB). The first models contained 42 million transistors, used the 0.18 micron process and came in 423-pin and 478-pin PGA packages. Intel's first Pentium 4 chipset was the 850 and supported only Rambus memory (RDRAM), but subsequent chipsets switched to DDR SDRAM. See NetBurst.

Celeron - Introduced in 1998 (266 MHz-2.8 GHz)
Less expensive Pentium chips due to smaller L2 caches. First Celerons had no L2 cache, but 128KB on-die cache was added in 1999. Celerons started out with 66 and 100 MHz system buses that migrated to 400 MHz.

Pentium III - 1999-2001 (500 MHz-1.13 GHz)
The Pentium III added 70 additional instructions to the Pentium II. The Pentium III used a 100 or 133 MHz system bus and either a 512KB L2 cache or a 256KB L2 Advanced Transfer Cache. Depending on the model, it contained from 9.5 to 28 million transistors, used the 0.25 or 0.18 micron process and came in SECC and SECC2 packages. Mobile units came in BGA and micro-PGA (µPGA) packages.

Pentium III Xeon - 1999-2001 (500-933 MHz)
Typically used in 2-way to 8-way servers, Xeon specs were like Pentium III with L2 cache up to 2MB. The Xeon used the SECC2 and SC330 chip packages.

Pentium II - 1997-1999 (233-450 MHz)
Added MMX multimedia instructions to Pentium Pro and introduced the Single Edge Connector Cartridge (SECC) for Slot 1. The Pentium II used a 66 or 100 MHz system bus. Desktop models had 7.5 million transistors, 512KB L2 cache and were housed in SECC packages. Mobile models had 27.4 million transistors, 256KB L2 cache and were housed in either BGA or Mobile Mini-Cartridge (MMC) packages.

Pentium II Xeon - 1998-1999 (400-450 MHz)
Typically used in high-end and 2-way and 4-way servers, Xeon specs were like Pentium II with L2 cache from 512KB to 2MB and 100 MHz system bus.

Pentium Pro - 1995-1997 (150-200 MHz)
Typically used in high-end desktops and servers, the Pentium Pro increased memory from 4GB to 64GB. The Pentium Pro had L2 cache from 512KB to 1MB, used a 60 or 66 MHz system bus, contained from 5.5 to 62 million transistors. It was made with 0.35 process and housed in a dual cavity PGA package. When introduced, it was touted as being superior to the Pentium for 32-bit applications.

Pentium MMX - 1997-1999 (233-300 MHz)
Added MMX multimedia instructions to Pentium CPU and increased transistors to 4.5 million. Desktop units used PGA package and 0.35 process while mobile units used TCP and 0.25 process.

Pentium - 1993-1996 (60-200 MHz)
First Pentium CPU models. The Pentium had an L2 cache from 256KB to 1MB, used a 50, 60 or 66 MHz system bus and contained from 3.1 to 3.3 million transistors built on 0.6 to 0.35 process. Chips were housed in PGA packages.

            Maximum        MultimediaModel      Memory  Gen**  Instructions

 Pentium 4    4GB    NB   MMX, SSE, SSE2
 P4 Xeon      64GB   NB   MMX, SSE, SSE2

 Celeron      4GB    P6   MMX

 PIII Xeon    64GB   P6   MMX, SSE
 Pentium III  4GB    P6   MMX, SSE
 PII Xeon     64GB   P6   MMX
 Pentium II   4GB    P6   MMX
 Pentium Pro  64GB   P6

 Pentium MMX  4GB    P5   MMX
 Pentium      4GB    P5

 **Code name for architecture generation
   NB = NetBurst architecture

   MMX added 57 instructions (see  MMX)
   SSE added 70; SSE2 added 144 (see  SSE)