The Intel CPU chip used in first-generation PCs (XT class). It was the brother of the 8086 chip, but used an 8-bit data bus instead of 16 bits. The 8088 was chosen by IBM to encourage migration from the 8-bit CP/M environment to DOS. CP/M was the predominant operating system for business applications in the early 1980s. See 8086 and x86.

Technical Specs
Type: 16-bit multitasking microprocessor; 8-bit bus

Transistors: 25,000

Package: 40-pin CERDIP

Registers: 14 16-bit

Addressing mode (later called Real Mode): Addresses 1MB memory.

80286 Processor

Central processing unit

An Intel 80286 Microprocessor
Produced	From 1982 to early 1990s
Common manufacturer(s)	Intel AMD Harris Corporation Siemens AG
Max CPU clock	6 MHz to 25 MHz
Min feature size	1.5 µm
Instruction set	x86-16 (with MMU)
Package(s)	PLCC 68-pin

The Intel 286^[1], introduced on February 1, 1982, (originally named 80286, and also called iAPX 286 in the programmer's manual) was an x86 16-bit microprocessor with 134,000 transistors.

It was widely used in IBM PC compatible computers during the mid 1980s to early 1990s.

After the 6 and 8 MHz initial releases, it was subsequently scaled up to 12.5 MHz. (AMD and Harris later pushed the architecture to speeds as high as 20 MHz and 25 MHz, respectively.) On average, the 80286 had a speed of about 0.21 instructions per clock. ^[2] The 6 MHz model operated at 0.9 MIPS, the 10 MHz model at 1.5 MIPS, and the 12 MHz model at 1.8 MIPs.^[3]

The 80286's performance was more than twice that of its predecessors (the Intel 8086 and Intel 8088) per clock cycle. In fact, the performance increase per clock cycle of the 80286 over its immediate predecessor may be the largest among the generations of x86 processors. Calculation of the more complex addressing modes (such as base+index) had less clock penalty because it was performed by a special circuit in the 286; the 8086, its predecessor, had to perform effective address calculation in the general ALU, taking many cycles. Also, complex mathematical operations (such as MUL/DIV) took fewer clock cycles compared to the 8086.

80386 Processor

Central processing unit

Intel 80386 DX, 16 MHz, foreground
Produced	From 1986 to September 2007
Common manufacturer(s)	Intel AMD IBM
Max CPU clock	12 MHz to 40 MHz
Min feature size	1.5 µm to 1 µm
Instruction set	x86 (IA-32)
Socket(s)	132-pin PGA, 132-pin PQFP; SX variant: 100-pin

The Intel 80386, otherwise known as the Intel386, i386 or just 386, is a microprocessor which has been used as the central processing unit (CPU) of many personal computers and workstations since 1986.

As the original implementation of the 32-bit form of the 8086-architecture, the i386 instruction set, programming model, and binary encodings is still the common denominator for all 32-bit x86 processors.^[1] As such, it has remained virtually unchanged for over 20 years, enabling modern processors to run most programs written for earlier chips, all the way back to the original 16-bit 8086 of 1978.

Successively newer implementations of this same architecture have become several hundred times faster than the original i386 chip during these years (or thousands of times faster than the 8086). A 33 MHz i386 was reportedly measured to operate at about 11.4 MIPS. [2]

The i386 was launched in October 1985, but full-function chips were first delivered in 1986^[vague]. Mainboards for 386-based computer systems were at first expensive to produce but were rationalized upon the 386's mainstream adoption. The first personal computer to make use of the 386 was designed and manufactured by Compaq[3].

In May 2006 Intel announced that production of the 386 would cease at the end of September 2007. [4] Although it had long been obsolete as a personal computer CPU, Intel, and others, had continued to manufacture the chip for embedded systems, including

80486 Processor

Central processing unit

The exposed die of an Intel 80486DX2 microprocessor.
Produced	From 1989 to 2007
Common manufacturer(s)	Intel IBM
Max CPU clock	16  MHz to 100 MHz
FSB speeds	16 MHz to 50 MHz
Min feature size	1, 0.8, 0.6 µm
Instruction set	x86
Cores	1
Socket(s)	Socket 1 Socket 2 Socket 3

The Intel 486, otherwise known as the 80486, i486, or just 486, was the first tightly pipelined x86 design. Introduced in 1989, it was the first x86 chip that used more than a million transistors, due to a large on-chip cache and an integrated floating point unit. It represents a second generation of 32-bit x86 designs, following the original 32-bit x86 processor, the Intel 80386, and a fourth generation of binary compatible CPUs since the 8086.

Pentium I Processor

A high-performance microprocessor introduced by Intel in 1993 as a successor to the 80286, 386, and 486. If the original numbering scheme had been followed, the chip would have been called the 586; the name Pentium derives from the Greek word pente (‘five'). Undoubtedly the change in nomenclature was intended to emphasize that the Pentium was a 65-bit processor as compared to the 16-bit 80286 and 32-bit 386 and 486. The original Pentium was succeeded by the Pentium Pro in 1996, the Pentium II in 1997, and the Pentium III in 1999. Another variant was the Pentium MMX, which in 1996 introduced embedded multimedia capability.

Pentium II Processor

Pentium III Processor

* Dual independent bus (DIB) architecture

* 100 MHz front-side bus speed

* A multi-transaction system bus

* MMX support

Pentium IV Processor

Central processing unit

Produced	From 2000 to 2008
Common manufacturer(s)	Intel
Max CPU clock	1.3 GHz to 3.8 GHz
FSB speeds	400 MT/s to 1066 MT/s
Min feature size	0.18 µm to 0.065 µm
Instruction set	x86 (i386), x86-64, MMX, SSE, SSE2, SSE3
Microarchitecture	NetBurst
Socket(s)	Socket 423 Socket 478 LGA775
Core name(s)	Willamette Northwood Prescott Cedar Mill

The Pentium 4 brand refers to Intel's line of single-core mainstream desktop and laptop central processing units (CPUs) introduced on November 20, 2000^[1] (August 8, 2008 was the date of last shipments of Pentium 4s^[2]). They had the 7th-generation architecture, called NetBurst, which was the company's first all-new design since 1995, when the Intel P6 architecture of the Pentium Pro CPUs had been introduced. NetBurst differed from the preceding Intel P6 - of Pentium III, II, etc. - by featuring a very deep instruction pipeline to achieve very high clock speeds^[3] (up to 4 GHz) limited only by max. power consumption (TDP) reaching up to 115 W in 3.6–3.8 GHz Prescotts and Prescotts 2M^[4] (a high TDP requires additional cooling that can be noisy or expensive). In 2004, the initial 32-bit x86 instruction set of the Pentium 4 microprocessors was extended by the 64-bit x86-64 set.

Pentium 4 CPUs introduced the SSE2 and SSE3 instruction sets to accelerate calculations, transactions, media processing, 3D graphics, and games. They also integrated Hyper-threading (HT), a feature to make one physical CPU work as two logical and virtual CPUs. The Intel's flagship Pentium 4 also came in a low-end version branded Celeron (often referred to as Celeron 4), and a high-end derivative, Xeon, intended for multiprocessor servers and workstations. In 2005, the Pentium 4 was complemented by the Pentium D and Pentium Extreme Edition dual-core CPUs.

ALL PROCESSOR INFORMATION

Pentium

Family of microprocessors developed by Intel Corp. Introduced in 1993 as the successor to Intel's 80486 microprocessor, the Pentium contained two processors on a single chip and about 3.3 million transistors. Using a CISC (complex instruction set computer) architecture, its main features were a 32-bit address bus, a 64-bit data bus, built-in floating-point and memory-management units, and two 8KB caches. It was available with processor speeds ranging from 60 megahertz (MHz) to 200 MHz. The Pentium quickly became the processor of choice for personal computers. It was superseded by ever faster and more powerful processors, the Pentium Pro (1995), the Pentium II (1997), the Pentium III (1999), and the Pentium 4 (2000).

For more information on Pentium, visit Britannica.com. Britannica Concise Encyclopedia. Copyright © 1994-2008 Encyclopædia Britannica, Inc.

A family of 32-bit CPU chips from Intel. The term may refer to the chip or to a PC that uses it. Pentium chips have been the most widely used in the world for general-purpose computing. The last of the series were the dual-core Pentium 4 models, and the Pentium was superseded by the Core in 2006 (see Intel Core).

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). Numerous Pentium models were introduced with increased performance. The Pentium uses a 64-bit internal bus compared to 32-bits in its 486 predecessor. Note that Intel's next-generation Itanium chip departed entirely from the Pentium architecture (see Itanium), while the Core line, which superseded the Pentium, retained the x86 instruction architecture for compatibility. 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 and the last of the Pentium line. 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         Multimedia
   Model            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 generation of architecture
    NB = NetBurst architecture

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