- Great Painters
- Accounting
- Fundamentals of Law
- Marketing
- Shorthand
- Concept Cars
- Videogames
- The World of Sports

- Blogs
- Free Software
- Google
- My Computer

- PHP Language and Applications
- Wikipedia
- Windows Vista

- Education
- Masterpieces of English Literature
- American English

- English Dictionaries
- The English Language

- Medical Emergencies
- The Theory of Memory
- The Beatles
- Dances
- Microphones
- Musical Notation
- Music Instruments
- Batteries
- Nanotechnology
- Cosmetics
- Diets
- Vegetarianism and Veganism
- Christmas Traditions
- Animals

- Fruits And Vegetables


  1. Adobe Reader
  2. Adware
  3. Altavista
  4. AOL
  5. Apple Macintosh
  6. Application software
  7. Arrow key
  8. Artificial Intelligence
  9. ASCII
  10. Assembly language
  11. Automatic translation
  12. Avatar
  13. Babylon
  14. Bandwidth
  15. Bit
  16. BitTorrent
  17. Black hat
  18. Blog
  19. Bluetooth
  20. Bulletin board system
  21. Byte
  22. Cache memory
  23. Celeron
  24. Central processing unit
  25. Chat room
  26. Client
  27. Command line interface
  28. Compiler
  29. Computer
  30. Computer bus
  31. Computer card
  32. Computer display
  33. Computer file
  34. Computer games
  35. Computer graphics
  36. Computer hardware
  37. Computer keyboard
  38. Computer networking
  39. Computer printer
  40. Computer program
  41. Computer programmer
  42. Computer science
  43. Computer security
  44. Computer software
  45. Computer storage
  46. Computer system
  47. Computer terminal
  48. Computer virus
  49. Computing
  50. Conference call
  51. Context menu
  52. Creative commons
  53. Creative Commons License
  54. Creative Technology
  55. Cursor
  56. Data
  57. Database
  58. Data storage device
  59. Debuggers
  60. Demo
  61. Desktop computer
  62. Digital divide
  63. Discussion groups
  64. DNS server
  65. Domain name
  66. DOS
  67. Download
  68. Download manager
  69. DVD-ROM
  70. DVD-RW
  71. E-mail
  72. E-mail spam
  73. File Transfer Protocol
  74. Firewall
  75. Firmware
  76. Flash memory
  77. Floppy disk drive
  78. GNU
  79. GNU General Public License
  80. GNU Project
  81. Google
  82. Google AdWords
  83. Google bomb
  84. Graphics
  85. Graphics card
  86. Hacker
  87. Hacker culture
  88. Hard disk
  89. High-level programming language
  90. Home computer
  91. HTML
  92. Hyperlink
  93. IBM
  94. Image processing
  95. Image scanner
  96. Instant messaging
  97. Instruction
  98. Intel
  99. Intel Core 2
  100. Interface
  101. Internet
  102. Internet bot
  103. Internet Explorer
  104. Internet protocols
  105. Internet service provider
  106. Interoperability
  107. IP addresses
  108. IPod
  109. Joystick
  110. JPEG
  111. Keyword
  112. Laptop computer
  113. Linux
  114. Linux kernel
  115. Liquid crystal display
  116. List of file formats
  117. List of Google products
  118. Local area network
  119. Logitech
  120. Machine language
  121. Mac OS X
  122. Macromedia Flash
  123. Mainframe computer
  124. Malware
  125. Media center
  126. Media player
  127. Megabyte
  128. Microsoft
  129. Microsoft Windows
  130. Microsoft Word
  131. Mirror site
  132. Modem
  133. Motherboard
  134. Mouse
  135. Mouse pad
  136. Mozilla Firefox
  137. Mp3
  138. MPEG
  139. MPEG-4
  140. Multimedia
  141. Musical Instrument Digital Interface
  142. Netscape
  143. Network card
  144. News ticker
  145. Office suite
  146. Online auction
  147. Online chat
  148. Open Directory Project
  149. Open source
  150. Open source software
  151. Opera
  152. Operating system
  153. Optical character recognition
  154. Optical disc
  155. output
  156. PageRank
  157. Password
  158. Pay-per-click
  159. PC speaker
  160. Peer-to-peer
  161. Pentium
  162. Peripheral
  163. Personal computer
  164. Personal digital assistant
  165. Phishing
  166. Pirated software
  167. Podcasting
  168. Pointing device
  169. POP3
  170. Programming language
  171. QuickTime
  172. Random access memory
  173. Routers
  174. Safari
  175. Scalability
  176. Scrollbar
  177. Scrolling
  178. Scroll wheel
  179. Search engine
  180. Security cracking
  181. Server
  182. Simple Mail Transfer Protocol
  183. Skype
  184. Social software
  185. Software bug
  186. Software cracker
  187. Software library
  188. Software utility
  189. Solaris Operating Environment
  190. Sound Blaster
  191. Soundcard
  192. Spam
  193. Spamdexing
  194. Spam in blogs
  195. Speech recognition
  196. Spoofing attack
  197. Spreadsheet
  198. Spyware
  199. Streaming media
  200. Supercomputer
  201. Tablet computer
  202. Telecommunications
  203. Text messaging
  204. Trackball
  205. Trojan horse
  206. TV card
  207. Unicode
  208. Uniform Resource Identifier
  209. Unix
  210. URL redirection
  211. USB flash drive
  212. USB port
  213. User interface
  214. Vlog
  215. Voice over IP
  216. Warez
  217. Wearable computer
  218. Web application
  219. Web banner
  220. Web browser
  221. Web crawler
  222. Web directories
  223. Web indexing
  224. Webmail
  225. Web page
  226. Website
  227. Wiki
  228. Wikipedia
  229. WIMP
  230. Windows CE
  231. Windows key
  232. Windows Media Player
  233. Windows Vista
  234. Word processor
  235. World Wide Web
  236. Worm
  237. XML
  238. X Window System
  239. Yahoo
  240. Zombie computer

This article is from:

All text is available under the terms of the GNU Free Documentation License: 


From Wikipedia, the free encyclopedia

Pentium logo, with MMX enhancement
Pentium logo, with MMX enhancement

The Pentium is a fifth-generation x86 architecture microprocessor from Intel. It was the successor to the 486 line, and was first shipped on March 22, 1993.

The Pentium was expected to be named 80586 or i586, to follow the naming convention of previous generations. However, Intel was unable to convince a court to allow them to trademark a number (such as 486), in order to prevent competitors such as Advanced Micro Devices from branding their processors with similar names (such as AMD's Am486). Intel enlisted the help of Lexicon Branding to create a brand that could be trademarked. The Pentium brand was very successful, and was maintained through several generations of processors, from the Pentium Pro to the Pentium Extreme Edition. Although not used for marketing purposes, Pentium series processors are still given numerical product codes, starting with 80500 for the original Pentium chip.

Intel has now largely retired the Pentium brand and replaced it with the "Intel Core" brand, although a future line of value processors will use the Pentium and Celeron brands[1]. The first Intel Core, released in January 2006, extended the Pentium M microarchitecture. The Intel Core 2, released in July 2006, features the new Intel Core microarchitecture.

Microsoft and many other companies use the original Pentium as a standard for specifications of requirements. For example, Microsoft's stated requirements for the Microsoft Visual Studio 2005 Team Edition, include (at least) a Pentium processor running at a clock speed of 600MHz (required), or 1GHz (recommended). To find out if another processor meets the requirement, a conversion must be used that gives its speed in terms of standard Pentium clock rates. For example, a Pentium Pro would meet the requirement running at a much lower clock speed, because of its more advanced architecture. An equivalency chart is usually used to compare more modern processors to find out if they meet this requirement.

In programming, it is sometimes necessary to distinguish the original Pentium processor architecture from later (P6 or P68-based) Pentium-branded architectures. For these cases, i586 is is a common, though spurious, way to refer to the early Pentium processors, as well as processors made by Intel's competitors that can run machine code targeted to the early Pentiums.

Major changes from the 486

Pentium Overdrive for 486 systems
Pentium Overdrive for 486 systems
  • Superscalar architecture - The Pentium has two datapaths (pipelines) that allow it to complete more than one instruction per clock cycle. One pipe (called "U") can handle any instruction, while the other (called "V") can handle the simplest, most common instructions. The use of more than one pipeline is a characteristic typical of RISC processors designs, the first of many to be implemented on the x86 platform, thus signaling the road to take, and showing that it was possible to merge both technologies, creating almost ôhybridö processors.
  • 64-bit data path - This doubles the amount of information pulled from the memory on each fetch. This doesn't mean that the Pentium can execute 64-bit applications; its main registers are still 32 bits wide.
  • MMX instructions (later models only) - A basic SIMD instruction set extension designed for use in multimedia applications.

Pentium architecture chips offered just under twice the performance of a 486 processor per clock cycle. The fastest Intel 486 parts were almost the same speed as a first-generation Pentium, and the AMD Am5x86 was roughly equal to the Pentium 75.


The earliest Pentiums were released at the clock speeds of 66 MHz and 60 MHz. Later on 75, 90, 100, 120, 133, 150, 166, 200, and 233 MHz versions gradually became available. 266 and 300 MHz versions were later released for mobile computing. Pentium OverDrive processors were released at speeds of 63 and 83 MHz as an upgrade option for older 486-class computers.

  • * These were only available as Mobile Pentium MMX chips for laptops.

P5, P54C, P54CS

Pentium 75 MHz (P54C, 80502)
Pentium 75 MHz (P54C, 80502)

The original Pentium microprocessor had the internal code name P5 and the product code 80501 (80500 for the earliest steppings). This was a pipelined in-order superscalar microprocessor, produced using a 0.8 Ám process. It was followed by the P54C (80502), a shrink of the P5 to a 0.6 Ám process, which was dual-processor ready and had an internal clock speed different from the front side bus (it's much more difficult to increase the bus speed than to increase the internal clock). In turn, the P54C was followed by the P54CS, which used a 0.35 Ám process - a pure CMOS process, as opposed to the Bipolar CMOS process that was used for the earlier Pentiums.

The early versions of 60-100 MHz Pentiums had a problem in the floating point unit that, in rare cases, resulted in reduced precision of division operations. This bug, discovered in Lynchburg, Virginia in 1994, became known as the Pentium FDIV bug and caused great embarrassment for Intel, which created an exchange program to replace the faulty processors with corrected ones. The 60 and 66 MHz 0.8 Ám versions of the Pentium processors were also known for their fragility and their (for the time) high levels of heat production - in fact, the Pentium 60 and 66 were often nicknamed "coffee warmers". They were also known as "high voltage Pentiums", due to their 5V operation. The heat problems were removed with the P54C, which ran at a much lower voltage (3.3V). P5 Pentiums used Socket 4, while P54C started out on Socket 5 before moving to Socket 7 in later revisions. All desktop Pentiums from P54CS onwards used Socket 7. Another bug known as f00f bug was discovered soon afterwards, but fortunately, operating system vendors responded by implementing workarounds that prevented the crash.

The P24 Pentium OverDrive for 486 systems, a sort of oddity among the other Pentium processors, was released in early 1995. The Pentium architecture had to be modified in many ways to operate on the 486 platform's narrower 32-bit data bus and slower cache architecture. As such, the chip came equipped with a 32 KB L1 cache, double what a pre-P55C Pentium came equipped with. The chip also included an attached fan/heatsink assembly in addition to onboard power regulation to convert the 5V power circuitry on 486 boards down to the Pentium's 3.3V needs.

P55C, Tillamook

Pentium MMX 233 MHz (P55C, 80503) top
Pentium MMX 233 MHz (P55C, 80503) top
Pentium MMX 166 MHz without cover
Pentium MMX 166 MHz without cover

The P55C (or 80503) was developed by Intel's Research & Development Center in Haifa, Israel. It was sold as Pentium with MMX Technology (usually just called Pentium MMX); although it was based on the P5 core (the 0.35 Ám process was also used for this series) it featured a new set of 57 "MMX" instructions intended to improve performance on multimedia tasks, such as encoding and decoding digital media data.

The new instructions work on new data types: 64-bit packed vectors of either eight 8-bit integers, four 16-bit integers, two 32-bit integers, or 1 64-bit integer. So, for example, the PADDUSB (Packed ADD Unsigned Saturated Byte) instruction adds two vectors, each containing eight 8-bit unsigned integers together, pairwise; each addition that would overflow saturates, yielding 255, the maximum unsigned value that can be represented in a byte. These rather specialized instructions generally require special coding by the programmer for them to be used. MMX did not achieve significant popularity until after the P55C's lifetime.

The performance of the P55C was improved over previous versions by a doubling of the Level 1 CPU cache from 16 KiB to 32 KiB.

Pentium P55C notebook CPUs used a "mobile module" that held the CPU. This module was a PCB with the CPU directly attached to it in a special smaller form factor. The module snapped to the notebook motherboard and typically a heat spreader plate was installed and made contact with the module. Such notebooks frequently used the Intel 430MX chipset, a feature-reduced 430FX. However, with the 0.25 μm Tillamook Mobile Pentium MMX (named after a city in Oregon), the module also held the 430TX chipset along with the system's 512 KiB SRAM cache memory.

Other uses of Pentium trademark

Pentium III chip mounted on a motherboard
Pentium III chip mounted on a motherboard

Intel has retained the Pentium trademark for naming later generations of processor architectures, which are internally quite different from the Pentium itself:

  • Pentium Pro
  • Pentium II
  • Pentium III
  • Pentium 4
  • Pentium M
  • Pentium D
  • Pentium Extreme Edition
  • Pentium E2000

It can be seen from this that brand name is only loosely related to the nature of a CPU's microarchitecture. The Pentium brand is traditionally used for desktop and notebook parts, the Celeron brand is used for "value" parts (typically lower performance and lower price), and the Xeon brand is used for high-performance parts suitable for servers and workstations. The same basic microarchitecture may be used for all brands, but implementations may differ in clock speeds, cache sizes, and package and sockets. Moreover, the same name is used for chips with unrelated microarchitectures.

The Intel Core processor uses the same microarchitecture as the Pentium M processors, but discards the Pentium M name (and also uses Intel's new logo). However the Pentium name will continue to be used in a new line of Core 2-derived processors. These processors, codenamed Conroe-L, will be marketed as the Pentium E2000 series. The new Pentium will have 1 MB of L2 cache and use an 800 MHz FSB, Intel EM64T technology, and Execute Disable Bit, and will be a dual-core processor.


5th generation x86 competitors

  • Nx586
  • 5x86
  • 5k86
  • WinChip
  • mP6

See also

  • Pentium Compatible Processor
  • CPU design
  • IA-32 processor design and instruction set


  1. ^ Huynh, Anh. Intel "Conroe-L" Details Unveiled. Daily Tech. Retrieved on 2006-09-23.

External links

  • - Intel Pentium images and descriptions
  • Plasma Online Intel CPU Identification


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