logo.gif (4185 bytes)

bar1.gif (700 bytes)bar2.gif (803 bytes)bar3.gif (888 bytes)bar4.gif (738 bytes)bar5.gif (814 bytes)bar6.gif (798 bytes)barx.gif (571 bytes)
dotblue.gif (38 bytes)


Other Pages

Site map
Computer help

What's new

dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)

tab4.gif (1598 bytes)tab2.gif (1635 bytes)tab.gif (1820 bytes)

Information about the computer CPU.


Heat sinks
Math coprocessors
Compatible Intel processors
Known CPU bugs
Intel socket information
Processor history and information
Technical Support
Processor definitions


The CPU or the Central Processing unit is the brain of the computer and the single most important chip in the computer. Modern processors contain millions of transistors which are etched onto a tiny square silicon called a die, which is about the with of a standard thumb. The CPU performs the system's calculating and processing. The majority of personal computers included the Intel processors. Intel released the first processor, the 4004 in 1970. Today the market is being shared by other companies such as the popular AMD processor manufactured by the AMD company.


Math coprocessors were additional chips which could be purchased with 386 and older chips. This additional chip was left as an option to help reduce the cost of computers. Coprocessors allow  the hardware for floating-point math. Math coprocessors will speed your computer's operation when utilizing software applications that take advantage of its capabilities. Computers now no longer require the extra purchase of the math compressor. Below is a listing of computer processors and their coprocessors.

Processor Coprocessor
8086 8087
8088 8087
80286 80287
80386SX 80387SX
80386SL 80387SX
80386SLC 80387SX
80486SLC 80387SX
80486SLC2 80387SX
80386DX 80387DX
80486SX 80487SX, DX2/Overdrive
80487SX Included FPU
80486SX2 DX2/Overdrive
80486DX Included FPU
80486DX2 Included FPU
80486DX4 Included FPU
Pentium/Pentium-MMX Included FPU
Pentium Pro Included FPU
Pentium II Included FPU
Pentium III Included FPU


Several companies such as AMD and Cyrix are also developing processors which are completely compatible with Intel processors. This means that they are capable of emulating every processor instruction in the the Intel chips.


dotwhite.gif (38 bytes)dotwhite.gif (38 bytes) dotwhite.gif (38 bytes)dotwhite.gif (38 bytes) KNOWN CPU BUGS

80386 - Some 386DX 16MHz Intel processors had small bug which appeared as a software problem. The bug involved occurred when running true 32-bit code in a program such as within OS/2 2.x, UNIX/386, or Windows in Enhanced mode. The bug would cause the system to lock ups and is a difficult issue to determine without having Intel actually look at the chip. Chips that passed the test, and all subsequent chips which were bug-free, were marked with a double-sigma symbol. 386DX chips that are not marked with either of these symbols may have not been tested by Intel and may be defective.

PENTIUM - One of the most famous and most known bugs is the Pentium FPU flaw / bug discovered by a a mathematician in October 1994. This bug involved the Pentium incorrectly performing floating-point calculations with certain number combinations, with errors anywhere from the third digit on up. This issue does not occur on 120MHz and above Pentium computers however is known to occur on Intel Pentiums 100MHz and below.

Ways of testing your Pentium CPU to determine if it has the Pentium flaw.

Correct Answer
962,306,957,033 / 11,010,046 = 87,402.6282027341

Incorrect Answer
962,306,957,033 / 11,010,046 = 87,399.5805831329

Correct Answer
4,195,835 / 3,145,727 = 1.33382044913624100

Incorrect Answer
4,195,835 / 3,145,727 = 1.33373906890203759

Another way of testing for this flaw is to use Microsoft Excel and enter the following formula:


When entering this formula you should receive a returned result of 0.


A number of Intel Motherboards incorrectly support the Write Back mode of the Intel Pentium OverDrive processor. Because of this you will be unable to successfully upgrade your CPU. However to rectify this issue Intel created a chip called the interposer. This chip allows the computer to work around the design errors.

Documentation for installing the interposer should be included with the interposer. If by chance documentation is not included you can find alternate installation help at Intel's web site (Search for Interposer).

dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)
INDEX question.gif (172 bytes)
dotgrey.gif (48 bytes)


See Network

Related Pages:
Heat Sink


DRIVERS question.gif (172 bytes)
dotgrey.gif (48 bytes)
No Specific drivers for this topic.

See Drivers Page for complete listing of drivers.


RESOLVED question.gif (172 bytes)
dotgrey.gif (48 bytes)
Were you able to locate the answer to your questions?




dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)


Intel designed a set of sockets. Each of these sockets supported a certain range of processors. Below we have listed the complete specifications and layouts of each of these sockets.

socket1.gif (3425 bytes) SOCKET 1 SPECIFICATIONS
169 Pins 17 x 17 PGA 5v SX / SX2, DX/DX2, DX4 OverDrive


socket2.gif (3916 bytes) SOCKET 2 SPECIFICATIONS
238 19 x 19 PGA 5v SX/SX2, DX/DX2, DX4 OverDrive, 486 Pentium OverDrive
socket3.gif (3925 bytes) SOCKET 3 SPECIFICATIONS
237 19 x 19 PGA 5v/3.3v SX/SX2, DX/DX2, DX4 OverDrive, 486 Pentium OverDrive
socket4.gif (3760 bytes) SOCKET 4 SPECIFICATIONS
273 21 x 21 PGA 5v Pentium 60/66MHz, Pentium 60/66 OverDrive
socket5.gif (5173 bytes) SOCKET 5 SPECIFICATIONS
320 37 x 37 PGA 3.3v Pentium 75-133, Pentium 75+ OverDrive
socket6.gif (3931 bytes) SOCKET 6 SPECIFICATIONS

Slot 6 was thought and planed of however was never actually ever implemented in any system.

235 19 x 19 PGA 3.3v DX4, 486 Pentium OverDrive
socket7.gif (4305 bytes) SOCKET 7 SPECIFICATIONS
321 37 x 37 PGA Voltage Regulator Module Pentium 75-300, Pentium 75+ OverDrive
slot1.gif (2508 bytes) SLOT 1 SPECIFICATIONS
242 Slot Voltage Regulator Module Pentium II / Pentium III Processors



Below is a listing of all known manufacturers made to date. The following list lists the processors manufactured in date order as well as a brief description of the technology and advances of each of the processors.

INTEL 4004 - Microprocessor introduced in 1970 with the speed of 108KHz was the worlds first microprocessor.

INTEL 8080 - Microprocessor introduced in 1974 running at the speed of 2 MHz was used in the world's first PC, the Altair.

INTEL 8086 (Code Name: P1)- Microprocessor first introduced in 1976. The 80086 had a 16-bit architecture that allowed it to work with 16-bit binary numbers and pass them through a 16-bit data bus. The 8086 was available in clock speeds of 5MHz, 8MHz, and 10MHz.

MOTOROLA 6800 - Microprocessor released in 1979 was later chosen by Apple for the Macintosh computer.

INTEL 8087 - Floating-point math compressor compliant with the 8086 / 8080 microprocessor family.

INTEL 8088 - Microprocessor released in 1979. The 8088 was the first Processor used in the original IBM PC and XT personal computers because it was less expensive than the 8086 microprocessor because of the availability of less expensive eight-bit data bus supporting chips made it the microprocessor for the IBM PC. The 8088 was available in speeds from 4.77 MHz and 8MHz.and used the 16-bit architecture allowing it to work internally with 16-digit numbers. The 8088 had the ability of addressing up to 1MB of RAM.

INTEL 80286 (Code Name: P2) - Microprocessor introduced by Intel in 1982. Which commonly is referred to as the 286 processor. The 286 processor supported 16-bit architecture, supported virtual memory, and was available in clock speeds of 8MHz, 10MHz, and 12MHz. The 286 was around 20 times faster then the predecessor 8088.

INTEL 80287 - A compliant processor to the 286. A floating-point math coprocessor. Specially designed 286 chips have the capability of placing the optional 80287 processor on top of it. Giving the computer a math coprocessor.

INTEL 80386DX (Code Name: P3) - Microprocessor manufactured in 1985 was the next generation of Intel processors. The 80386DX included the math compressor unlike the 80386SX and still featured the 32-bit architecture and built-in multitasking. The chip was available in clock speeds of 16MHz, 20MHz,  25MHz, and 33MHz.

SPARC - Released in 1987 is short for Scaleable Processor  ARChiture by Sun - used RISC (Reduced Instruction Set) to speed up processing.

INTEL 80486DX (Code Name: P4) - Microprocessor released April 10th 1989. The 486DX featured a built-in memory cache and 32-bit architecture. It had more than three times the computing power of the 386DX and was available in clock speeds of 25MHz, 33MHz, and 50MHz.

INTEL 80386SX - Microprocessor introduced in 1989 was the next generation of Intel processors. The 80386SX lacked a math coprocessor however still featured the 32-bit architecture and built-in multitasking. The chip was available in clock speeds of 16MHz, 20MHz,  25MHz, and 33MHz.

INTEL 80386SL - Microprocessor introduced in 1990 which used low power consumption and was used mainly in portable computers.

INTEL 80486SX (Code Name: P45 / P23 ) - Microprocessor introduced in April 1991 which is a less expensive version of the 80486DX. It lacked the math coprocessor of the 80486DX and ran at lower clock speeds then the DX it ran at 16MHz, 20MHz, 25MHz, or 33 MHz.

INTEL 80486DX2 (Code Name: P24 / P24S) - Microprocessor first introduced in March 2, 1992. It was based upon the popular 486DX however featured internal clock speeds that doubled that of the system that operated it. Thus, a DX2 on a system with a 33MHz bus would run at 66MHz. Also known as the i486DX2.

INTEL 80486DX4  (Code Name: P24C / P24CT)- Microprocessor first introduced in 1994. The 486DX4 would triple that of the system that operated it.

INTEL PENTIUM (Code Name: P5 (Pentium 60 - 66MHz))- Microprocessor introduced March 22, 1993 designed to replace the 486 processors. The new Pentium had an additional 1.9 million transistors when compared to the 80486DX. The Pentium has a 32-bit address bus and a 64-bit data bus, and it can operate at speeds of 60MHz to 200MHz. The Pentium was released in three generations. The first-generation of Pentium processors was the Pentium 60 and 66 MHz. These chips used a 273-pin PGA form factor and ran on 5v power. Intel announced the release of a second-generation introduced March 7, 1994 included new processors from 75, 90, 100, 120, 133, 150, 166, and 200 MHz. The processors used 296-pin SPGA form factor that is physically incompatible with the first generation versions. The third-generation of Pentium processors code named P55C were introduced January 1997,  which incorporated the new technology MMX. The Pentium MMX processors were available 166, 200, 233 MHz, and 266 MHz mobile version.

INTEL PENTIUM PRO (Code Name: P6) - Microprocessor which was designed for the corporate users and for high-end servers and workstations, preferably those using Windows NT.  The Pentium Pro CPUs are extremely fast with 32-bit applications and 3-D image processing and rendering when compared to previous Intel processors. The chip runs at 166MHz and higher

INTEL PENTIUM II (Code Name: Klamath) - Initially the Pentium II 233MHz was released in 1997 and introduced a new physical architecture which encased a circuit board within a plastic case. With this new technology this allowed the chip to be easily added and removed. However previous owners of Pentium motherboard could not upgrade to this new type of chip unless the motherboard they had included a SLOT 1 technology. The Pentium II runs from 233MHz to 450MHz.

INTEL PENTIUM III - Initially the Pentium III 500 MHz was released in 1999 shortly after its released Intel introduced the Pentium III 550 MHz processor. The Pentium III chip continued to use the SLOT 1 and could be used on previous Pentium II motherboards with BIOS support. Before its release a big controversy concerning privacy. The Intel Pentium III chips have a ID for each chip helping to authenticate peoples purchase over the Internet. However many argued that this was another way for someone to find out personal information about the individual without there consent. Intel disabled this feature by default and allowed it to be released after   released the chip.


Reference Issue / Question
CHADD Additional information with installing computer hardware.
CH000044 Can a AMD and Intel processor work together.
CH000046 How do I determine the speed of my processor?
CH000098 What's ODP / ODPR?
CH000099 CPU Upgrade questions and answers.
CH000100 Is there a way to tell how hot my CPU is running?
CH000103 I have a Intel Pentium III+, how do I disable the serial number?


top.gif (407 bytes)

logo.gif (4185 bytes)
dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)dotwhite.gif (38 bytes)

Computer Hope

Technical Information and Help | Professional Web Design
http://www.computerhope.com    http://www.computerhope.net

Other Pages Main Page | On-line Help | Contact | Search | Products | Network
Games | Art/Images | HTML Help | Virus Info | Search
Advertise | Link to Computer Hope | Book Mark Computer Hope