A CPU History

The history of the processor is an interesting one, full of fierce competition and advanced technology, yet short in the terms of years. At the point where I will begin addressing this history, we are beginning with a 5 MHz 8086 processor, and today we are routinely seeing 1.8 GHz to up over 2 GHz. What a difference 20-some years can make. Let us start.


In the Beginning, there was 8086…


CPUs have gone through many changes through the few years since Intel came out with the first one. IBM chose Intel’s 8088 processor for the brains of the first PC. This choice by IBM is what made Intel the perceived leader of the CPU market. Intel remains the perceived leader of microprocessor development. While newer contenders have developed their own technologies for their own processors, Intel continues to remain more than a viable source of new technology in this market, with the ever-growing AMD nipping at their heels.


The first four generations of Intel processor took on the “8″ as the series name, which is why the technical types refer to this family of chips as the 8088, 8086, and 80186. This goes right on up to the 80486, or simply the 486. The following chips are considered the dinosaurs of the computer world. PC’s based on these processors are the kind that usually sit around in the garage or warehouse collecting dust. They are not of much use anymore, but us geeks don’t like throwing them out because they still work. You know who you are.



  • Intel 8086 (1978)
    This chip was skipped over for the original PC, but was used in a few later computers that didn’t amount to much. It was a true 16-bit processor and talked with its cards via a 16 wire data connection. The chip contained 29,000 transistors and 20 address lines that gave it the ability to talk with up to 1 MB of RAM. What is interesting is that the designers of the time never suspected anyone would ever need more than 1 MB of RAM. The chip was available in 5, 6,, 8, and 10 MHz versions.

  • Intel 8088 (1979)
    The 8088 is, for all practical purposes, identical to the 8086. The only difference is that it handles its address lines differently than the 8086. This chip was the one that was chosen for the first IBM PC, and like the 8086, it is able to work with the 8087 math coprocessor chip.

  • NEC V20 and V30 (1981)
    Clones of the 8088 and 8086. They are supposed to be about 30% faster than the Intel ones, though.

  • Intel 80186 (1980)
    The 186 was a popular chip. Many versions have been developed in its history. Buyers could choose from CHMOS or HMOS, 8-bit or 16-bit versions, depending on what they needed. A CHMOS chip could run at twice the clock speed and at one fourth the power of the HMOS chip. In 1990, Intel came out with the Enhanced 186 family. They all shared a common core design. They had a 1-micron core design and ran at about 25MHz at 3 volts. The 80186 contained a high level of integration, with the system controller, interrupt controller, DMA controller and timing circuitry right on the CPU. Despite this, the 186 never found itself in a personal computer.

  • Intel 80286 (1982)
    A 16-bit, 134,000 transistor processor capable of addressing up to 16 MB of RAM. In addition to the increased physical memory support, this chip is able to work with virtual memory, thereby allowing much for expandability. The 286 was the first “real” processor. It introduced the concept of protected mode. This is the ability to multitask, having different programs run separately but at the same time. This ability was not taken advantage of by DOS, but future Operating Systems, such as Windows, could play with this new feature. On the the drawbacks of this ability, though, was that while it could switch from real mode to protected mode (real mode was intended to make it backwards compatible with the 8088′s), it could not switch back to real mode without a warm reboot. This chip was used by IBM in its Advanced Technology PC/AT and was used in a lot of IBM-compatibles. It ran at 8, 10, and 12.5 MHz, but later editions of the chip ran as high as 20 MHz. While these chips are considered paperweights today, they were rather revolutionary for the time period.

  • Intel 386 (1985 – 1990)
    The 386 signified a major increase in technology from Intel. The 386 was a 32-bit processor, meaning its data throughput was immediately twice that of the 286. Containing 275,000 transistors, the 80386DX processor came in 16, 20, 25, and 33 MHz versions. The 32-bit address bus allowed the chip to work with a full 4 GB of RAM and a staggering 64 TB of virtual memory. In addition, the 386 was the first chip to use instruction pipelining, which allows the processor to start working on the next instruction before the previous one is complete. While the chip could run in both real and protected mode (like the 286), it could also run in virtual real mode, allowing several reasl mode sessions to be run at a time. A multi-tasking operating system such as Windows was necessary to do this, though. In 1988, Intel released the 386SX, which was basically a low-fat version of the 386. It used the 16-bit data bus rather than the 32-bit, and it was slower, but it thus used less power and thus enabled Intel to promote the chip into desktops and even portables. In 1990, Intel released the 80386SL, which was basically an 855,00 transistor version of the 386SX processor, with ISA compatibility and power management circuitry.
    386 chips were designed to be user friendly. All chips in the family were pin-for-pin compatible and they were binary compatible with the previous 186 chips, meaning that users didn’t have to get new software to use it. Also, the 386 offered power friendly features such as low voltage requirements and System Management Mode (SMM) which could power down various components to save power. Overall, this chip was a big step for chip development. It set the standard that many later chips would follow. It offered a simple design which developers could easily design for.

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Comments

  1. Your Notes are very clear and Excelent. If you can update to current, it is very good.

    Thank you

  2. Your notes have helped me a lot about something i’ve been looking for in the past week.your Your notes are excelent thanx

  3. Just to point out that you state the 80186 never made it into a personal computer, however i owned a 186 system around 1992 that was made my Research Machines.
    Just thought you would like to know.

    • There was also a Tandy / Radio Shack PC that used an 80186. Just one model that didn’t last for more than a year. Their usual black and silver case. I can’t swear that it was 100% compatible with the usual instruction sets that software depended on.

      • Hugh Wyn Griffith says:

        That Tandy 186 was the Tandy 2000 and its graphics were not 100% compatible with Windows much to the distress of users (I was one when I bought my first “almost-PC” in the UK back in the ’90′s). This caused a lot of ill feeling between users and Tandy. The Users Group launched a monthly called “Orphans” and hated Ed Juge (who died recently) the then CEO of Tandy for not providing any support.

        I was amused a few years ago when Googling on Tandy 2000 to pull up a full page advert for it from one of the well known magazines at that time in which Bill Gates lauded it saying how much his programmers depended on it for its performance! Might explain some of Windows problems if they were using a non-conforming PC !

    • u probably have the one that was made in 1990 then that was the 1 that did make it in2 the personal computer as is later stated in there

  4. The 5×86 was not AMD’s answer to the Pentium, the P5 was. The 5×86 was made to offer a greater performance boost to the millions of 486 PC’s out there, as it would work in (almost) any 486 motherboard with a socketed CPU or overdrive socket.

  5. Chris, It doesn’t say it was AMD’s answer. It was their “competitive response to Intel’s Pentium-class processor”
    on a 486 motherboard.

    Also, not mentioned is why Intel went from a number designation to a name title, the number, was actually the stock number. As I was told by a Intel Rep. at a Comdex show (Vegas) ’94-’95. As Intel tried to sue AMD for copy right infringement. Like a fragrance, you can’t CR. the recipe only the name. They lost on the grounds, you can’t copy right a stock number (80486)! So they, Intel started using name designation (Pentium). As well as AMD did the same.

  6. This is great, im supposed to be at work, but im reading this, just spent quite a while reading it. Its very interesting, Thank You

  7. Bill Buchanan says:

    Correction to information provided on the Intel 80186 (1980).
    This Processor was used in one desk top system but the system did not sell well. The company was Tandy and the model was Tandy 2000. There is a very good page at: http://www.old-computers.com/museum/computer.asp?c=1219 covering the processor.

  8. Mick Russom says:

    Acorn’s Master 512 PC had a 10MHz 80186 CPU which ran MS-DOS and GEM. I would say this qualifies it as a “PC” running a 80186 running MS-DOS.

  9. Sandy Jelusic says:

    I have at home an pc desktop powered by an 8088 at 3.5 mhz with turbo mode, black-yellow monitor, 20mb disk and only 5.25” floppy. As for dos I think it’s ibm-dos. Not really certain.

  10. Very knowledgeful. Please update with latest changes.

  11. Really your services are good we like it please keep it up.

  12. chelle-marie says:

    that is great i loved the little joke:

    “The following chips are considered the dinosaurs of the computer world. PC’s based on these processors are the kind that usually sit around in the garage or warehouse collecting dust. They are not of much use anymore, but us geeks don’t like throwing them out because they still work. You know who you are.”

    sounds just like my tech teacher becouse he is always complaining about how things have changed and shows us pictures from back when computers still used tapes and how he used to get paid to change the tapes every two hours for a hospitle

  13. Mary Alice Thauvette says:

    This article was posted 23-Mar-01. That was nine years ago. It is time to update the article. Or, at least change the title of the last section from :1999 – Present” to “1999 – March 2001″

  14. what is the significances of the number like 8086 in the processor

  15. thanks for the notess

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