A detailed history of the processor

Cyrix 6×86 Series (1995)

Cyrix, by this time, was a major player in the alternative processor market. They had been around since 1992, with their release of the 486SLC. By 1995, they had their own 5×86 processor and it was considered the only real competition to the AMD counterpart. But, they released their 6×86 in 1995. It was designed to go head to head with Intel’s Pentium processor. Dubbed “M1”, the chip contained two super-pipelined integer units, an on-die FPU, and 16 KB of write-back cache. It used many of the same techniques internally as the Intel and AMD chips to increase performance. Like AMD beginning with their K5 (see below), Cyrix used the P-rating system. It came in PR-120, 133, 150, 166 and 200 versions. Each rating had a “+” after it, indicating that it performed better than the corresponding Pentium. But, did it?

Cyrix had had a reputation for lagging in the area of performance, and the M1 was not an exception. The chip used a weaker FPU than both AMD and Intel, meaning it could not keep up with the competition in areas such as 3D gaming or other math-intensive software. On top of that, the chip had a reputation for running hot. Users had to get CPU fans that could keep these hot processors cool enough to run stably. Cyrix tried to combat this issue with the 6x86L processor. This “low power” processor made use of a split voltage (3.3 volts for I/O and 2.8 volts internally).

MediaGX (1996)

MediaGX was Cyrix’s answer to low-cost entry level PC’s. Making use of a standard x86 processor core, the chip lowered the cost of PCs using it by integrating many of the common PC components into the chip itself. MediaGX had integrated audio and video circuitry, as well as circuitry to handle many of the common tasks normally handled by chips on the motherboard itself. The CPU spoke directly to a PCI bus and DRAM memory, and the video was rather high-quality SVGA (for the time). It could support up to 128 MB of EDO RAM in 4 separate memory banks, and the video sub-system could support resolutions of up to 1280x1024x8 or 1024x768x16.

The integration of MediaGX was actually spanned across two chips: the processor itself and the MediaGX Cx5510. The chip requires a specially designed motherboard. It is not Socket 7 compatible. As a result, it is really an outsider in relation to the other processors we were discussing, but being that it was on the timetrack of history for CPUs, it bears mentioning.

AMD K5 (1996)

While AMD was competing with Intel with their 5×86 processor, this chip was not a true Pentium alternative. In 1996, however, AMD released the K5. This chip was designed to go head to head with the Pentium processor. It was designed to fit right into Socket 7 motherboards, allowing users to drop K5’s into the motherboards they might have already had. The chip was fully compatible with all x86 software. In order to rate the speed of the chips, AMD devised the P-rating system (or PR rating). This number identified the speed as compared to the true Intel Pentium equivalent. K5’s ran from 75 MHz to 166 MHz (in P-ratings, that is). They contained 24KB of L1 cache and 4.3 million transistors. While the K5’s were nice little chips for what they were, AMD quickly moved on with their release of K6.

Pentium MMX (1997)

Intel released many different flavors of the Pentium processor. One of the more improved flavors was the Pentium MMX, released in 1997. It was a move by Intel to improve the original Pentium and make it better serve the needs in the multimedia and performance department. One of the key enhancements, and where it gets its name from, is the MMX instruction set. The MMX instructions were an extension off the normal instruction set. The 57 additional streamlined instructions helped the processor perform certain key tasks in a streamlined fashion, allowing it to do some tasks with one instruction that it would have taken more regular instructions to do. It paid off, too. The Pentium MMX performed up to 10-20% faster with standard software, and higher with software optimized for the MMX instructions. Many multimedia applications and games that took advantage of MMX performed better, had higher frame rates, etc.

MMX was not the only improvement on the Pentium MMX. The dual 8K caches of the Pentium were doubled to 16 KB each. It also had improved dynamic branch prediction, a pipelined FPU, and an additional instruction pipe to allow faster instruction processing. With these and other improvements, the Pentium line of processor was extended even longer. The line lasted up until recently, and went up to 233 MHz. While new PCs with this processor are all but non-existent, there are many older PCs still using this processor and going strong.

AMD K6 (1997)

The K6 gave AMD a real leg up in performance, and it virtually closed the gap between Intel and AMD in terms of Intel being perceived as the real performance processor. The K6 processor compared, performance-wise, to the new Intel Pentium II’s, but the K6 was still Socket 7 meaning it was still a Pentium alternative. The K6 took on the MMX instruction set developed by Intel, allowing it to go head to head with Pentium MMX. Based on the RISC86 microarchitecture, the K6 contained seven parallel execution engines and two-level branch prediction. It contained 64KB of L1 cache (32KB for data and 32KB for instructions). It made use of SMM power management, leading to mobile version of this chip hitting the market. During its life span, it was released in 166MHz to 300 MHz versions. It gave the early Pentium II’s a run for their money, but AMD had to improve on it in order to keep up with Intel for long.

Cyrix 6x86MX (1997)

Well, Intel came up with MMX and AMD was already using it starting with the K6. So, Cyrix had to get in on the game as well. The 6x86MX, also dubbed “M2”, was Cyrix’s answer. This processor took on the MMX instruction set, as well as took an increased 64KB cache and an increase in speed. The first M2’s were 150 MHz chips, or a P-rating of PR166 (Yes, M2’s also used the P-rating system). The fastest ones operated at 333 MHz, or PR-466.

M2 was the last processor released by Cyrix as a stand-alone company. In 1999, Via Technologies acquired the Cyrix line from it’s parent company, National Semiconductor. At the same time, Via also acquired the Centaur processor division from IDT.

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  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

  16. amandu benard says:

    i love the notes they are precise and straight to key needed aspects thank you very much

  17. roger crouch says:

    This article lacks credibility. The first chip of the series was the 8080, then the 8085 was made (the 5 indicating it only needed +5v and ground instead of +-5 and +12) https://www.quora.com/What-is-the-difference-between-8085-and-8086 So the only true thing that can be said about the 8086 was that it was 16bit 8080 processor with improved IC features and more command set.

    • Mike Spooner says:

      From certain perspectives, the “first chip of the series” was the 4004 (1971), or pehaps the 8008 (1972), the 4040 (1974), 8080 (1974), or…

      In fact, the 8080 external interface was distinctly different from the 8086, in idea, not just width – for example, 8080 pin 21 (DMA acknowledge).

      The 8086 was (almost) binary compatible with the 8080 for “regular programs” ie: not ones that twiddled ports nor relied on specific interrupt/trap behaviour.

      So where do you draw the line? Where does Bob draw it? WHere does Fiona draw it? All in different places, I suspect.

      The author obviously chose to draw their line at the 8086, probably because delving back beyond the original IBM PC machines might not be worthwhile given a presumed intended audience…

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