The Intel 4004 used MOS (metal–oxide–semiconductor) transistors.

What has been the transistor types used in Intel processors onwards from the 4004 to 8085 to the x86 family of instruction set architectures?

There are probably complications such as maybe some processors are composed of more than one transistor type or there may be more than say ten different transistor types, from the 4004 to present day. So if needed to simplify the answer detailing the main transistor types used or trends would be fine.

Any commentary on advantages of a change of transistor type over the previous one is also welcome.

  • 1
    they've been MOS the entire time. JFETs are essentially useless for making logic circuits, and BJTs waste a lot of power.
    – Hearth
    Sep 3, 2020 at 0:57
  • 1
    This is a good summary and useful for highlighting why certain transistors are not used. Wikipedia says “bipolar transistor integrated circuits were the main active devices of a generation of mainframe and mini computers, but most computer systems now use integrated circuits relying on field effect transistors”. Which tallies with the Intel processors since MOS and MOSFET seem to mean the same thing. Sep 3, 2020 at 5:38
  • 2
    Yes, MOS in this context--and most contexts--is just a shortening of MOSFET.
    – Hearth
    Sep 3, 2020 at 9:53

1 Answer 1


Here’s the list of main technologies used:

  • 4004: 10µm PMOS;
  • 4040: 10µm PMOS;
  • 8008: 10µm PMOS;
  • 8080: 6µm NMOS (faster than PMOS, and TTL-compatible);
  • 8085: 3.2µm NMOS, then HMOS (“H” variants);
  • 8086: 3.2µm NMOS, then HMOS (in three iterations) and CHMOS (static variants);
  • 80186: 3.2µm HMOS and CHMOS;
  • 80286: 1.5µm HMOS (also CMOS, at least from other manufacturers);
  • 80386: 1.5µm CHMOS, then 1µm CHMOS;
  • 80486: 1µm CHMOS initially;
  • Pentium: 0.8µm BiCMOS, down to 0.35µm;
  • Pentium Pro: 0.6µm BiCMOS, down to 0.35µm;
  • Pentium MMX: 0.28µm CMOS (which Intel referred to as 0.35µm because the transistor density is the same as 0.35µm BiCMOS used in previous Pentiums);
  • Pentium II: 0.35µm CMOS, then 0.25µm;
  • Pentium III: 0.25µm CMOS, down to 0.18µm;
  • Pentium 4: 0.18µm CMOS, down to 65nm;
  • Core 2: 65nm CMOS, then 45nm.

Since then, the main technology remains CMOS, with smaller pitches, down to 7nm FinFETS in the latest CPUs.

  • Thanks—this is exactly what was looking for. Do you know what the static means in static variants of the 8086? Sep 2, 2020 at 14:22
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    It means they keep their state, and need very little (if any) power to do so; this is the same as “static” in “static RAM”. Early microprocessors had static variants for applications where power consumption was important; this isn’t specific to Intel CPUs, there were others (e.g. the 65C02). Sep 2, 2020 at 14:25
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    More importantly, "Static" means it is possible to stop or slow down the processor clock for an arbitrary amount of time without losing the internal state (i.e. registers, program counter, pipelines etc.). Non-static microprocessors (which includes most early μPs) would need to keep running in order to be "refreshed" (similarly to DRAMs).
    – StarCat
    Sep 2, 2020 at 16:01
  • Just found the Static Core Wikipedia page about this. I vaguely remember they sent an x86 processor into space and it was presumably one of these variants? How were these x86 static variants used, presumably a software change? Sep 2, 2020 at 16:56
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    SRAM still needs some power to keep state. Leakage current is small but non-negligible if we're talking about fully removing power for any significant interval. (The smaller the transistor size, the larger the leakage current as a fraction of total power. So it's a much more significant issue for modern CPUs than early 8086; e.g. modern CPUs power down their caches when entering deep sleep states to save even more power than just gating the clock (which they also do aggressively to currently-unused parts of each core because that does still matter a lot).) Sep 3, 2020 at 5:14

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